Why aren't computers designed to handle power failure? - Page 1
Forum section: electronics / general

author: Raj
author_rank: Frequent Contributor
timestamp: June 12, 2020, 07:28:40 am
content: It came as a surprise to me that even in America, where all the computers are designed one might have to face one or two unplanned short power outages every month.To Stop computers from crashing, we use UPS...Now the thing is, UPS converts 12v to 220v which is used to power computer, occasionally a monitor and maybe bunch of other peripherals when all that was needed to save the computer was a continuous power to the volatile memory and a little bit of power to the processor and other memory to give it enough time to send itself to sleep.This would be most efficient if the battery were to directly interact with the motherboard.Why don't we do this?

author: daqq
author_rank: Super Contributor
timestamp: June 12, 2020, 07:42:09 am
content: QuoteMost notably because of the extra expenses and overall pointlessness. UPS devices here are rare. I know of one person who has their work computer hooked up to an UPS (notebooks don't count since they do this by default). And no one wants to change batteries, the extra weight etc.I wouldn't want an extra compartment in my desktop for an event that has happened once this year (power outage) and even that was because a colleague was very creative when it came to hooking up cables.An extra connector would be an option but again, that's another expense that maybe 1% of the people would use.edit: Servers are a different thing of course, but powering data centers is a very different story.

author: oPossum
author_rank: Super Contributor
timestamp: June 12, 2020, 07:55:43 am
content: It is being done for servers. For example...https://www.supermicro.com/products/nfo/files/BBP/f_BBP.pdf

author: filssavi
author_rank: Frequent Contributor
timestamp: June 12, 2020, 08:08:44 am
content: I assume the OP is only talking about desktop computer, as servers are a whole different world (there UPSes are basically ubiquitous, and things like storage arrays and disk/raid controllers even have their own battery backed RAM)It just is a matter of complexity against usefulness...Let's start off by saying that there are very, very few workloads where a power outage is actually an issue, mainly workstations running long simulations (days to weeks long). otherwise a power failure is nothing more than a nuisance. So from the start the benefits of designing something outage proof are minimal.Now apart from when performing certain kinds of major updates, the OSes are actually designed so that the disk always stays in a consistent state, so in case of a power outage the system is still bootable and stable, thus the downside is only the loss of what is in memory.The addition of outage resiliency would also be extremely complex in the current market for economic/technical reasons:- Backward compatibility: anything you do, if you want any hope of widespread adoption, it must be backward compatible with the ATX standard, mostly dating back to the 90's, so good luck.- all PSUs now need to be intelligent enough to reliably detect a power loss and report it to the main processor, realistically the only way is coaxing intel into adding it to the ATX standard, because:A) it needs to be universal, not a different communication method for eack PSU OEMB) you actually need the OEMs to implement it in something other than their halo products, which is of questionable feasibility given the already razor thin margins in what ammounts to a commodity market- Also software will probably need to be aware of emergency shutdown, as you only need to save the bare minimum to resume work (trying to save 16-32 GB to a bunch of spinning rust would realistically require way too much energy- The solution will need to be batteryless (you can't expect a consumer to regularly replace batteries every couple of years, and beside good luck trying to find spare batteries for old motherboards

author: Raj
author_rank: Frequent Contributor
timestamp: June 12, 2020, 08:24:46 am
content: "people won't like to replace batteries"Meanwhile, we third world guys have to deal with using desktops cause it's too hot for laptops to not thermal throttle. But the ups are so horrible, they just save your pc from dying twice, then the battery is useless (doesn't keep the PC alive it'll it's done shutting down) *attached photo of said battery*Specially since window 10 takes forever to shutdown the computer. (Night and day difference between it and Linux)That should add a special emergency shutdown procedure.And adding a optical isolated universal power failure detection port for computer to ups communication shouldn't be a big thing. Lots of motherboard have unused serial interface (rs232)I've been thinking of attaching my PC into one of those sine wave house inverters which use 150aH (I've seen their batteries lasting more than 5 years)Also I've herd that Intel is working on a motherboard system that takes on nothing but 12v, unlike ATX with its negative and positive voltages of every value that you can imagine being in a PCMaybe that'll make it happen. So backwards compatibility should not be an issue in near future.I wonder if the "economic reasons" is even a excuse, since most of the desktop computer users are in the third world. Cause Western normies often go for a laptop, even when they wanna game. And third world guys are happy to pay for a better one time solution than paying for reoccurring expense like changing battery every year.

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 08:29:36 am
content: Err, they are designed to handle power failures. You're just looking at the wrong end of the problem.https://en.wikipedia.org/wiki/Journaling_file_systemAlso most SSDs that aren't a piece of crap have "hold up" capacitors which allow the device to do a final consistent write in power failure scenarios (this is why you never buy cheap SSDs!).Even MS office does periodic auto-commits and flushing. You don't have to use the save button.

author: Krotow
author_rank: Regular Contributor
timestamp: June 12, 2020, 08:33:52 am
content: With improved and power outage (almost) safe file systems used almost everywhere it is not much an issue anymore. Who use FAT/FAT32 in their PC HDD/SDD-s anymore? Situations when power outage cause major file system corruption is quite rare now. Besides that any other solution will cause unnecessary complexity and compatibility issues. People above already described most of them.

author: Raj
author_rank: Frequent Contributor
timestamp: June 12, 2020, 08:36:24 am
content: Quote from: bd139 on June 12, 2020, 08:29:36 amGood thing, even crap modern hard drives are complex enough to not crash their heads into spinning disks and use the momentum of platter as an momentum battery to park their heads.Super useful if you're working in the third world where you're unlikely to find SSDs

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 08:46:30 am
content: Indeed.Bottom end SSDs are quite cheap now (120gb for $15 off market prices) which is e-waste price. I reckon they'll be turning up in large quantities in the third world now.

author: Raj
author_rank: Frequent Contributor
timestamp: June 12, 2020, 09:19:04 am
content: Funny enough, third world guys don't like to buy brands, they've never herd of. They'll rather buy an Intex that explodes the next day, than paq xi jin pin that'll last as long as they're alive. Marketing really works in such nations. Specially if you use patriotism, even if you're just a company that rebrands Chinese stuff

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 09:20:28 am
content: Not much different here to be honest!

author: filssavi
author_rank: Frequent Contributor
timestamp: June 12, 2020, 10:13:56 am
content: Quote from: Raj on June 12, 2020, 08:24:46 amI’m sorry if I came out rude, it really was not my intention. I feel your pain, however the fact of the matter is that development in PC technology is driven by developed “first world” countries needs, and here the power grids are stable enough that the odd crash once or twice a year is not an issue.Bolting the feature on after the fact is certainly doable, whether you can find a market large enough for it to be economically viable I’m not knowledgeable enough on markets where such a thing would be usefull

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 10:33:33 am
content: It happens in first world countries as well:http://news.bbc.co.uk/1/hi/england/london/8162511.stmGuess who was cooking off a alcohol stove then

author: Ian.M
author_rank: Super Contributor
timestamp: June 12, 2020, 11:09:40 am
content: ATX form factor combo PSU/UPSes are commercially available. Its a niche market but big enough to support a number of manufacturers.e.g.http://embedded-computing.com/news/trumpower-24v-battery-charger-2/No special motherboard support required except for a free internally accessible USB port.

author: dmills
author_rank: Super Contributor
timestamp: June 12, 2020, 11:16:30 am
content: Quote from: bd139 on June 12, 2020, 08:29:36 amWe got shafted by that at work, industrial controller PC that gets hard power off fairly often, turns out the SSD was lying about when it had committed data which left the fs overlapping the journal writes and the data writes, occasional hilarity ensued.Extensive testing of SSDs ensued, and the ONLY ones that really worked properly were the Intel ones (Which were not available in our required form factor), very annoying.

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 11:25:52 am
content: Samsung Pro 2.5" SATA units are fine as well. I found that the Samsung Pro M2 ones don't have hold up capacitors though as they are usually shoved in laptops. Figured to hell with it when I built my desktop and stuffed a Samsung Evo in it.HPE and Intel ones do.

author: daqq
author_rank: Super Contributor
timestamp: June 12, 2020, 11:36:33 am
content: QuoteLooking at the modern computer PSU, shouldn't they be able to run off of higher voltage DC? The input is rectified anyway.

author: pepelevamp
author_rank: Regular Contributor
timestamp: June 12, 2020, 12:39:01 pm
content: ** computer science guy joins the chatthe problem is that computers in principal should be able to turn off in the blink of an eye without any problem. yet we can't design general purpose computers without being drunk & smoking crack.if you truly think about it - aside from say saving an open document - why would you really even need to doanythingwhen you yank the power on a computer?now i know you're all gonna bite at me saying oh gee pepe, filesystems need to be flushed to disk oh waa. to that i say - stop cheating to get more performance with ya wee DRAM memory caches.anywhere that has a DRAM cache such as a disk must hold enough local power in a local supercap to flush it to disk.the modern day CPU is full of lies & tricks to get more performance by cheating. writing to local caches etc. its all a big scam. pipe-lining, speculative execution, asynchronous volatile buffers - its all stuff that takes away your ability to deterministically run operations in sequence - all just so you can get more overall throughput. it makes it damn near impossible to yank out your power cable and plug it back in again & resume at point T: Your computer never has one point in time that its working at. Its scattered.so I propose this:either give every damn thing a supercap or stop lying to everybody & make honest computers.it all falls apart anyway. look at speculative execution. the latest security screwup is so bad the only solution is to lock the entire memory bus & tank the system's performance by 97%.

author: engrguy42
author_rank: Frequent Contributor
timestamp: June 12, 2020, 12:40:45 pm
content: I'm kinda scratching my head here. While I realize this is probably a fun tech topic for some with nothing better to do, for the average home desktop user the stuff they're working on are, well, less than critical. You need a UPS so you don't lose your place in your favorite video game? Or that youtube video you were watching of a cat playing piano? Let's be real here.Also, W10 has a (sometimes annoying) feature where if it's shut off suddenly it remembers what you were working on and re-starts it all, where you left off, the next time you boot your computer. Add to that the fact that, for many/most here in the US, loss of power is a fairly rare occurrence. I generally go many months without an interruption. Yeah, in storm/hurricane season you might more, but it depends on where you live.Though I'm sure we'll hear from those "yeah, but..."'s who lost their power yesterday....Businesses are a different thing entirely, and they employ serious solutions as needed. And for home users, I recall my brief journey with a UPS many years ago was pretty much a waste, since it only provides enough power so you can take a few minutes to finish everything and shut it down. A lot of money for something like that...And of course the "yeah, but..."'s will have to mention how you can get a bigger one to last longer.

author: pepelevamp
author_rank: Regular Contributor
timestamp: June 12, 2020, 12:52:20 pm
content: yeah but computers are general purpose & theres little reason to yield to making computers unsafe to do work on, especially in the avenue of 'ya not doing anything important'. thats an uphill battle to prove.computers simply should not require any significant time to safely shut down. the blame for this goes directly to asynchronous instruction caches, multiple cores, pipelining, speculative execution and so-on.windows & applications have never been able to safely restore up to where they were. same with the mac. they dont actually do that. its just an attempt to do something similar enough in appearance to make you think you're resuming. ya not.OP is right more than he even realizes:computers are not designed to safely handle power failure. UPS externally or even an internal power buffer is still not making a computer designed to handle power failure - you're just eliminating or delaying the power failure.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 12, 2020, 12:56:28 pm
content: Quote from: filssavi on June 12, 2020, 08:08:44 amJust make it an ATX PSU with a standardized connection for a battery and USB for monitoring. In fact, with many modern ATX PSUs internally generating 5V and 3.3V from 12V using DC/DC converters and a 3S pack being just perfect for supplying 12V directly, it might not take much hacking to convert a PSU to do that.What I would like to see is an additional signal that instantly drops the CPU speed to minimum to allow using a smaller battery, I have DIYed one fairly easily by adding a circuit to a motherboard that pulls down the PROCHOT line.

author: Monkeh
author_rank: Super Contributor
timestamp: June 12, 2020, 01:10:54 pm
content: Quote from: Raj on June 12, 2020, 07:28:40 amAmerica must speak a lot of Chinese today.

author: madires
author_rank: Super Contributor
timestamp: June 12, 2020, 01:16:08 pm
content: Some statistics about power outages:https://www.indexmundi.com/facts/indicators/IC.ELC.OUTG/rankingsIn my case about 5 short outages happen a year, mostly in the summer during thunderstorms. The outages last for a few seconds up to a few minutes (<10). Longer outages are quite rare (maybe one in 5 years). There are also a few undervoltage events.

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 01:25:22 pm
content: Quote from: pepelevamp on June 12, 2020, 12:39:01 pmAlso comp sci guy. None of that really matters. All you need is a write barrier and transactional consistency. And we actually mostly have that.In a lot of cases we have much much much better than that with journaling and nice new formats (Redis AOF I fucking love) which allow full ordered consistency.

author: Bud
author_rank: Super Contributor
timestamp: June 12, 2020, 01:32:34 pm
content: What is the point of connecting a battery directly to the desktop computer if it is often required to also keep the display powered and may be some other peripherals. A mains voltage UPS already does that.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 12, 2020, 01:40:15 pm
content: As said. Cost, usefulness. Complexity. (That would be another potential point of failure and something to maintain - the batteries for instance.)As someone else said, thanks to reasonable filesystems and reasonable OSs, most computers can survive power loss with no harm done. I've certainly experienced quite a few in the past (before I used UPSs) and never damaged anything or lost any file due to that.Now if you want that very feature, it's easy. Buy a laptop.

author: pepelevamp
author_rank: Regular Contributor
timestamp: June 12, 2020, 02:20:26 pm
content: Quote from: bd139 on June 12, 2020, 01:25:22 pmyeah thats beautiful stuff. but saying ya only need transactional consistency is like saying 'its easy. to solve this problem all ya need is the problem solved'. how ya gonna get transactional consistency into a multi-core SMP dude-bro PC with shared and non-shared caches and no atomic operations?non-volatile memory is the ticket to all dis. CPUs can shut down & live on 0.001mA no problem but not dram.I had this old 286 with non-volatile memory. This old rugged handheld unit that weighed like over 2kg in your hand & was made of IRON & nickel or something. you could break a car window with it. ya could take out the batteries for up to 30 days and put em back in and resume ya work. No jokes. Little LCD screen with AA batteries. thats the kind of tough computer that bullies you into doing the work for it.

author: krish2487
author_rank: Frequent Contributor
timestamp: June 12, 2020, 02:38:19 pm
content: Going on a tangent here.. One reason I can think of why most UPS systems are not DC and AC is also the overall cost of transmission.It is pretty much the same reason why transmit AC rather than DC. Not withstanding small UPS systems which you place next to your PC, even a moderately sized installation for a couple of computers or even a small office will1. Not run off a single 12V, but a higher DC bus2. Cost of wiring to handle will be way expensive compared to a AC installation of a similar size. All the switchgear, safety circuits, wires will need to sized for DC.

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 02:41:07 pm
content: Quote from: pepelevamp on June 12, 2020, 02:20:26 pmI disagree. You're looking at one side of the set of problems.Memory consistency is irrelevant to the point. Your data is divided neatly into volatile and non volatile across a neat line in the storage hierarchy. You only need consistency across the volatility barrier, which you get from write barriers and transaction journaling. But that's not even the issue.As for transactional consistency I write highly concurrent, redundant and reliable code that works across NUMA machines with 48 cores and 1Tb+ of RAM. I suggest you read Hoare's CSP paper as an introduction to my favoured approach which doesn't need transactional memory or global atomicity. The reason none of that got implemented in our current state of the art architectures is because quite frankly it sucked.Complete non-volatility is distinctly NOT an option because you're only looking at power failure for one set of state. The entire machine's state consists of thousands of little pockets of state from IO registers, DRAM buffers, SMC registers, SPI bus transactions, PCI bus transactions in flight, CPU configuration registers etc. And we're only looking at the power failure scenario. How do we handle hardware failures or bus errors (sweep them under the carpet?). None of that can't be consistently rationalised by hardware really. As always it's easier to resolve the case of how to get from ground zero to a known state than it is to get from an unknown state to a known state.However the short cut and the correct answer is that the only thing that matters is the intent of what you are doing and recovering that intent from your non volatile store. So all you have to do is:1. make sure the intent is consistent on the part of the software writing to disk (sync + transaction journalling)2. that the data is written in an order that makes sense (write barriers)3. that the operation succeeds (last sata / nvme transaction was committed - hold up capacitors)This works for more than just power failure scenarios. Fires, halon dumps, APC UPS issues, wars, dodgy fibre cables and laptop PMC's giving up before the battery is dead.

author: pepelevamp
author_rank: Regular Contributor
timestamp: June 12, 2020, 02:53:12 pm
content: Quote from: bd139 on June 12, 2020, 02:41:07 pmValid. I yield to your logic.I'm still taking with me though my rant about computers being full of fibs & lies. I'm still afraid of intel's spooky-ghost execution and ya cant make me like it!

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 02:54:45 pm
content: Oh yes that's a complete shit show that is. Completely agree. And don't get me started on x86 as an architectureEdit: incidentallyhttp://danluu.com/cpu-bugs/. Ryzen here. Slightly less buggy

author: filssavi
author_rank: Frequent Contributor
timestamp: June 12, 2020, 02:57:55 pm
content: Quote from: NiHaoMike on June 12, 2020, 12:56:28 pmIf you want a one off prototype/ small production run I am shute you can hack together something that sort of works with a battery, am arduino and not much moreThat said the question was why is not a standard feature of all PCs. In that case with the volumes we are talking about, coupled to how anal the enthusiast market is (just waiting for the smallest technicality to raise a major shitstorm against anyone) you need something much better engineered and integrated.The hard part is the software not the hardware, and not from a CS perspective, it is the software engineering that kills you, making sure everything is compatible, right drivers, client software must not be too obstructive, backward compatibility, etc

author: ogden
author_rank: Super Contributor
timestamp: June 12, 2020, 02:59:54 pm
content: Quote from: Raj on June 12, 2020, 07:28:40 amWe indeed do this. In every laptop and tablet/handheld computer. Some time ago Google did that with server as well - gel battery plugged directly into motherboard.https://www.cnet.com/news/google-uncloaks-once-secret-server-10209580/

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 03:02:59 pm
content: Quote from: filssavi on June 12, 2020, 02:57:55 pmBTW you can use "picopsu" boards to do this and then use a standard BMC board as the supply for it.https://www.mini-itx.com/store/?c=10Don't expect to hang a Ryzen 9 off it

author: pepelevamp
author_rank: Regular Contributor
timestamp: June 12, 2020, 03:22:38 pm
content: Quote from: bd139 on June 12, 2020, 03:02:59 pmthanks a bunch now i have lost the rest of my life to this rabbit hole. what a fantastic idea. I have long wished that all the devices in my house simply ran off DC. you could have a stack of 18650s in there with a BMS and have your own sweet sensual UPS for a fraction of the cost of those horrible big nasty UPSes that just include those disgusting alternators with their jaggedy excuses for sine waves.

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 03:27:24 pm
content: I was working on a similar idea until recently. Decided not to bother in the end because the incompatibilities of all the things gave me a small headache every time I tried to resolve them. I have an SLA floating around, some LED lights that'll run of it, a laptop with extended battery and a Trangia stove worst case

author: Marco
author_rank: Super Contributor
timestamp: June 12, 2020, 03:33:26 pm
content: Quote from: Raj on June 12, 2020, 07:28:40 amCause no one big pushed it. If the ATX standard even had as an option a standardized DC input for UPS purposes, then things would have gone differently.

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 03:42:08 pm
content: There's an ATX12VO standard coming out this year which is standardised DC input for 12V. Design guide:https://www.intel.com/content/dam/www/public/us/en/documents/guides/single-rail-power-supply-platform-atx12vo-design-guide.pdf

author: filssavi
author_rank: Frequent Contributor
timestamp: June 12, 2020, 03:48:06 pm
content: Quote from: bd139 on June 12, 2020, 03:42:08 pmTrue but At least in the foreseeable future it will only be used in OEM systems ( think dell, HP and Lenovo) Discrete PSU and motherboard manufacturers have already said they don’t have any plan to implement it as it would fragment the market and lead to confusion in most consumers

author: bd139
author_rank: Super Contributor
timestamp: June 12, 2020, 04:16:36 pm
content: That's a bummer. There's enough fragmentation so I agree. I built my first desktop for about 10 years recently and was annoyed to find out that I still had to frig around with LED and power switch wiring like I did in the mid 1990s. Perhaps they can consolidate all that first.

author: filssavi
author_rank: Frequent Contributor
timestamp: June 12, 2020, 04:52:22 pm
content: I wholeheartedly agree with you, I personally think that in the long run always staying up to date as much as possible saves a load of time and headache.Unfortunately the rest of the computing world seems to revolve around lazy peoples, and either you go the apple route, discontinuing and changing what you want, and are thorougly hated for that, or you keep backwards compatibility essentially forever (ok usually 15/30 years, which is pretty much forever), as anyone else does.This means that no standard can be retired, and the infamous 14 standards xkcd is pretty much the only thing that happensCase and point the IPv4 to IPv6 transition, it has been going on for 20 years and will not be finished at least until 2040 in my opinion, all the while ipv4 is on life support (many peoples ask ARINC to issue also the 240.0.0.0/4 space, knowing full well that at the moment most of the routers on the planet do not support them, since they were not supposed to be used).

author: Raj
author_rank: Frequent Contributor
timestamp: June 12, 2020, 05:12:06 pm
content: Quote from: filssavi on June 12, 2020, 10:13:56 amNo, no, you weren't rude at all... Just, you didn't know what people of other countries going throughQuote from: Ian.MI didnt know that... ThanksQuote from: bd139 on June 12, 2020, 11:25:52 amLucky me, has a SamsungQuote from: pepelevamp on June 12, 2020, 12:39:01 pmYup, spectre and meltdown were pretty bad. But 97% performace degradation after patch? Wow! I didnt know thatQuote from: engrguy42That's why I like to use alt f4 instead of start menu. Man that stuff is super annoyingQuote from: Bud on June 12, 2020, 01:32:34 pmSince doing that will provide longer standby time with same battery otherwise one could always get "inverter" which can literally power a computer almost 40 times as long (I know that inverter battery is marked 150Ah and ups battery is marked 7Ah, but it's it really? Measure it and 7Ah will come out as 2Ah, since all of them are made by no name brand with no one caring to test em)Quote from: pepelevamp on June 12, 2020, 03:22:38 pmI too am trying to literally modify everything I own, to run off of 18650Quote from: bd139 on June 12, 2020, 04:16:36 pmHere's a tip, arrange them then hot glue em and then connect and peel the glue off. That way, you'll have to fumble around lessQuote from: filssavi on June 12, 2020, 04:52:22 pmAnd my isp is like adding NATs to NATs and splitting the bandwith like crazy

author: pepelevamp
author_rank: Regular Contributor
timestamp: June 12, 2020, 05:50:52 pm
content: Quote from: Raj on June 12, 2020, 05:12:06 pmOh mate. Me too. It is the best idea in the universe. I'm hooked on it. With a wee USB charger board or a boost here & there to get ya up to 5v if needed or regulate down to 3v3 - its just wonderful. the whole world should do this.

author: tom66
author_rank: Super Contributor
timestamp: June 12, 2020, 06:25:17 pm
content: I've had one power cut in the last 3 years. It should be uncommon enough that it doesn't cause major issue.

author: Raj
author_rank: Frequent Contributor
timestamp: June 13, 2020, 05:49:42 am
content: Quote from: tom66 on June 12, 2020, 06:25:17 pmMeanwhile...My company is giving free power to farmers, so that they can run their bore wells, while I get a 15 minute power cut daily. The problem wouldn't be there, if the cut was to happen on a set time, but it happens randomly at any moment.

author: firehopper
author_rank: Frequent Contributor
timestamp: June 13, 2020, 11:48:47 am
content: Quote from: bd139 on June 12, 2020, 04:16:36 pmyes I just upgraded a computer with a x570 MB and had to faf about with the front panel connectors, granted it was a lot simpler this time, as the connectors had the polarity marked on them and it was only 5 of them, so fairly easy and painlessit just worked. but thats part of the case design.

author: bd139
author_rank: Super Contributor
timestamp: June 13, 2020, 12:04:55 pm
content: Yeah mine worked first time as well which surprised me.I did see a picture the other day where the cable had two reset button connectors on it and no LED though

author: madires
author_rank: Super Contributor
timestamp: June 13, 2020, 01:45:09 pm
content: Anything wrong with that? It's the fun part of building your own PC.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 13, 2020, 04:56:16 pm
content: Quote from: pepelevamp on June 12, 2020, 03:22:38 pmA number of mini-ITX motherboards can already run off DC without any additional module. Of course don't expect high performance from this, but I've built a Linux box that is on my LAN and that I use for Linux dev tasks, based on a thin mini ITX MB (ASUS) with a Core i7 4790T and 16GB RAM. Not ridiculous. Runs off a DC adapter and is fully passively cooled (the case is made for this - it gets a bit hot under load, but never failed.)

author: bd139
author_rank: Super Contributor
timestamp: June 13, 2020, 05:02:39 pm
content: There are a few "canned" desktops which can do that as well. Lenovo M600's run off a 19V DC thinkpad chargerI'm using one as a media centre at the moment. Fanless Celeron that runs LibreElec + Kodi. Nice little machines. Also make handy Linux utility boxes as they run headless.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 14, 2020, 04:32:48 pm
content: Having an external UPS is actually quite good if you have more than one device you want to protect from power loss / brownouts.I have an ancient APC UPS (with a fresh battery!) under the desk, it is able to keep everything on the desk alive for about an hour after a power failure (i.e. the PC, test equipment, etc.). It can communicate with the PC so it can shut itself down safely. You could even write a program that shuts other things down safely, if the PC can be made to communicate with those things.

author: Raj
author_rank: Frequent Contributor
timestamp: June 14, 2020, 05:06:45 pm
content: Quote from: SilverSolder on June 14, 2020, 04:32:48 pmAn hour (as opposed to mine doing just 2 minutes max)? Holy cow, I need to get one

author: madires
author_rank: Super Contributor
timestamp: June 14, 2020, 05:42:09 pm
content: That's fairly simple, just oversize the UPS. Most datasheets state the runtime for full load and 50% load. If your load is 100VA a 200VA UPS might give you 8 minutes (3 minutes at full load). The 500VA model runs for 20 minutes, and the 1000VA UPS will give you 40. Several years ago my old UPS broke down but I had an old rackmount UPS from a datacenter at hand (large, heavy, 8 SLAs). That beast was able to power my SOHO datacenter for 3.5 to 4 hours. But it's no UPS you would usually place in you home office, so I bought a smaller SOHO friendly model which provides power for about half an hour with one server running.

author: bd139
author_rank: Super Contributor
timestamp: June 14, 2020, 06:33:25 pm
content: Comedy gold. I had a 1KVA APC which just exploded when the power went out. Was only three months old as well.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 14, 2020, 06:54:34 pm
content: Quote from: bd139 on June 14, 2020, 06:33:25 pmYou should know better than to buy new stuff!You need equipment with some experience...

author: bd139
author_rank: Super Contributor
timestamp: June 14, 2020, 07:01:50 pm
content: Hahaha probably right. Buy it after all the stuff made on a Friday afternoon has blown up

author: tkamiya
author_rank: Super Contributor
timestamp: June 21, 2020, 02:18:54 am
content: There was once a UNIX server computer that came with an UPS built-in. It was made by either NCR or AT&T, I don't remember. It was time when network scheme was proprietary. (no Ethernet) Unit was quite heavy but I thought it was quite innovative. Problem was, it was very hard to move, and very difficult to get to the battery. Pop-open door it was not!While I agree with OP that it would be nice. Perhaps super capacitor scheme or something to hold it up for 5 second or so. Personally, I'd like to have UPS external. Batteries die predictably, and I really don't want to take computers apart to deal with it. I have more than 10 running here. 2KVA external UPS works nicely. Easy maintenance.

author: John B
author_rank: Frequent Contributor
timestamp: June 21, 2020, 10:17:43 pm
content: Quote from: SilverSolder on June 14, 2020, 04:32:48 pmNot a SmartUPS 2200/3000XL or something perhaps? Here's inside the guts of a 2200XL aka "old faithful". The oldest date code in there is 2001. The current batteries in there are 9 years old! I'm only using it for very light duty stuff, and the frequency of running on the batteries is very low around here.It has a pure sine wave output, much cleaner than the grid. Between the 2 transformers, heatsinks, and the batteries, this thing weighs like 90lbs. Also have to be careful around those heatsinks, they're connected to the battery. Shorting out 55V at 100's of amps could get spicy.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 21, 2020, 11:17:55 pm
content: Quote from: John B on June 21, 2020, 10:17:43 pmI have a baby one compared to yours, but it still weighs in at a noticeable 27lbs! I believe it is from the late 90's and looks like this (not the exact unit):Mine has a brand new battery... the old one died a quiet and dignified death! The unit is very strong and like yours, gives beautiful clean output. They don't mak'em like this etc.!The software for these units is hopelessly outdated, that's the only real issue with them. There is an open-source project that supports them with power-down daemons, but I haven't had a play with that yet (I did manage to find one of the special serial cables needed...).What software do you use, if any?

author: John B
author_rank: Frequent Contributor
timestamp: June 21, 2020, 11:58:30 pm
content: There's d-sub com port on the back, but I never even thought to try and connect it. I haven't needed to change any of the settings. From the documentation it just has the usual, like turn on and off delays, low battery shutdown %, sensitivity to mains voltage high or low conditions etc.I'm currently also refurbishing an eaton ex 2200, which is maybe 10 years old, and still it was difficult to track down the software. Haven't got it working yet.I get the feeling the moment that a UPS manufacturer moves to the next model, the old ones and all support are buried in tombs. I figure that the business models demand that they push out new models constantly. This is reinforced by the fact that all my UPS units are salvaged - they were all destined for the garbage dump. Companies and workplaces replace the batteries maybe once, then turf the whole unit even though nothing else is wrong with them.

author: John B
author_rank: Frequent Contributor
timestamp: June 22, 2020, 12:02:55 am
content: So to answer the initial post - why not incorporate the UPS into a computer as a matter of course? Because you don't want to. It will be a horribly cheap compromised unit.Better to track down a good quality standalone unit that is being discarded and just needs some new batteries. You should be able to find one cheap, or better free

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 22, 2020, 12:34:00 am
content: Quote from: SilverSolder on June 21, 2020, 11:17:55 pmThere's apcupsd, of which one of its most interesting features is the ability to tie in all sorts of automation like CPU frequency control.http://www.apcupsd.org/manual/#customizing-event-handlingIt also looks like it would be easy to program an Arduino to emulate an APC UPS, for those who have a solar power setup with battery backup.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 22, 2020, 01:23:42 am
content: Quote from: NiHaoMike on June 22, 2020, 12:34:00 amThat's the one I was looking at, couldn't recollect the name when I posted!

author: SilverSolder
author_rank: Super Contributor
timestamp: June 22, 2020, 01:27:27 am
content: Quote from: John B on June 21, 2020, 11:58:30 pmAll mine can do is basically flap one of the pins in that serial port on the back (non standard, so requires a special cable) when the power fails, which signals the computer to shut down gracefully (if it has the right software running that can react to the flapping pin).Today, it would probably be designed to send some kind of cryptic messages that are difficult or impossible to work with...

author: Raj
author_rank: Frequent Contributor
timestamp: June 22, 2020, 04:27:06 am
content: Quote from: SilverSolder on June 22, 2020, 01:27:27 amThat's exactly what i've been thinking of implementing....I created a "shutdown shortcut" and assigned it the hotkey "Cltr+Shift+Alt+F4" ...Soon I'll make a microcontroller send my pc that hotkey via usb keyboard protocol whenever it detects a power failure. I've been thinking of using v-usb along with attiny but Vusb code is klingon to me

author: Berni
author_rank: Super Contributor
timestamp: June 22, 2020, 06:20:22 am
content: Quote from: SilverSolder on June 22, 2020, 01:27:27 amThese days they use USB with a HID driver. Still not quite all standard but there is open source software that works with most of the popular brands and models.I run a NAS server with Unraid and a UPS connected via USB. Does a pretty good job of it too as it shows up with a ton of information about the UPS such as battery state, current load, estimated backup time remaining, last self test status...etc and can be given a command to turn off the UPS once the OS has finished its shutdown process. Not sure what these periodic self tests do, but it sounds like it switches over to battery power for a few seconds (Maybe its using the load to measure the battery internal resistance to determine if its going to die) and i have no idea how is it supposed to notify me of a failed self test. Will it send a error over the USB or will it beep? No idea, but its only like 2 years old so the battery shouldn't fail yet.

author: madires
author_rank: Super Contributor
timestamp: June 22, 2020, 10:17:13 am
content: Quote from: SilverSolder on June 21, 2020, 11:17:55 pmAnother open source project is NUT (Network UPS tools) which supports most UPS vendors and is quite versatile. It also comes with some features intended for professional use. One drawback is that it doesn't support APC's MODBUS protocol yet (you would have to use an AP9605).

author: SilverSolder
author_rank: Super Contributor
timestamp: June 22, 2020, 01:05:57 pm
content: Quote from: Berni on June 22, 2020, 06:20:22 amInteresting, it might not be so hard to get an Arduino to act as the HID, converting between the "flapping serial pin" and HID, so modern software can be used... but then, it takes away from the authentic experience of using ancient equipment!

author: Raj
author_rank: Frequent Contributor
timestamp: June 22, 2020, 01:34:08 pm
content: Quote from: SilverSolder on June 22, 2020, 01:05:57 pmIndeed...I remember that keyboards used to have shutdown button. It should be just an hour of work to make a device that does the intended function.

author: bluey
author_rank: Regular Contributor
timestamp: June 27, 2020, 08:44:48 pm
content: A. Use a laptopB. Modern pcs with journalling filesystems are pretty robust without power protection except for the work you lose that hasn’t been autosaved. Hence A.C. Server class machines with dual redundant power supplies, battery backed caches, and external ups cost more. For home, see A.