Oh I messed up real bad, anyone good with PC motherboards? - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: November 26, 2018, 04:22:53 am
content: Hello you very helpful bunch.I purchased a NOS motherboard I needed for a specific project (vintage SCSI), the heatsinks wouldn't fit so I got some adapters, they seemed to work, the board powered on OK but froze at the BIOS, I tried a few more times and then I couldn't even get to the BIOS.I gave up and took the heatsinks off and I noticed the thermal paste hadn't been smudged, so the heatsinks weren't touching the top of the CPUs, nightmare, so I ordered some copper shims and tried a fresh CPU, nothing.So my guess is something has failed on the motherboards CPU (power) section, the CPU isn't even getting warm.It's a SuperMicro X7DB8+, is it for the bin, thoughts?Thanks.Richard

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: November 26, 2018, 04:42:31 am
content: checked the psu? also since it's dual socket, try individual cpu in each socket

author: rthorntn
author_rank: Frequent Contributor
timestamp: November 26, 2018, 06:54:47 am
content: Thanks ChunkyPastaSauce.I just tried a processor in the CPU2 socket, it booted to BIOS a few times but now nothing.When I was in the BIOS I could see the CPU temp was normal, I have a new 750W Corsair PSU so that shouldn't be the problem.I haven't been able to get the BIOS in the last 10 power cycles, it seems to have given up.

author: rdl
author_rank: Super Contributor
timestamp: November 26, 2018, 07:23:25 am
content: Computers can act weird if there's memory problems. Did you try removing and reinserting the memory? If there's more than one module, try booting with just one at a time. If you have any that's known good, try using that.

author: rthorntn
author_rank: Frequent Contributor
timestamp: November 26, 2018, 08:17:15 am
content: Tried 4 different RAM sticks one at a time.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: November 26, 2018, 09:16:49 am
content: Have you discharged the CMOS? It may have been corrupted when the processor crashed.Seen the situation before where a processor overheated and damaged the little SMPS for the core voltage, on the mobo. The processor itself was OK. You maybe need to find out which MOSFETS supply which voltages and check the outputs. Since they are usually buck converters, the choke will have the DC output voltage on it. (at both sides) Be very careful not to cause a short with the meter probe.

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 26, 2018, 11:13:48 am
content: Sounds like you may have cooked your CPU. Of course, trying another one may be precarious if you're not entirely sure what's at fault. Can you try it in another board?

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: November 26, 2018, 12:17:35 pm
content: There is a youtube channel from India where the producer fixes a lot of different motherboards. Its called Science and Research or something like that. Its not in English, but it is possible to follow what he's doing from the graphics.You should try watching how he troubleshoots these and it may give you a better idea of what to look for. I can't vouch for his methods or results. Hope this is helpful.

author: timgiles
author_rank: Regular Contributor
timestamp: November 26, 2018, 12:54:45 pm
content: I thought from the mid 2000's all CPUs had inbuilt thermal protection that allowed you to remove the heatsinks without causing damage. Or am I having a senior moment?Anyway, so have you tried just CPU and the minimum about of ram that CPU requires? You need to ensure that the memory is put in the correct channel as server boards can be picky and when running 1 CPU, it needs to be in at least the right bank of .... ´8. If you have not, try this, switch out the CPUs and memory so you try both CPUs in each socket (so 4 tests).

author: nsrmagazin
author_rank: Regular Contributor
timestamp: November 26, 2018, 01:25:34 pm
content: Why did you make the same mistake with the second slot, as you did with the first?There might be some internal defence which stops it after 10 times. Leaving it to rest might help.You have a high temp, a short, you broke the slot or you burned something else. It would be good to test the "CPU" on a different motherboard and the "RAM" also maybe.First get your act in order -> put the proper heatsinks, paste and then test. Also try to put your hand on the CPU, under the motherboard or on the heatsink and test the real CPU temperature (be careful not to burn yourself).Don't test until it fails again!Can you measure with a multimeter or an osciloscope? An osciloscope would be better if you have one. Try to measure the power supply first and then if possible the supply pins of the MCU. The MCU has power and ground on some pins.Do you have a video card on your motherboard (external, internal or both)?How is the chipset chip and the BIOS chip?

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 26, 2018, 01:54:12 pm
content: Quote from: rthorntn on November 26, 2018, 04:22:53 amwhat is the processor? can you remove everything from motherboard except monitor, keyboard and mouse. and try to power it up? if it fail, try to change PSU, if it still fail, try to change motherboard.

author: jc101
author_rank: Frequent Contributor
timestamp: November 26, 2018, 04:32:37 pm
content: Do you get any POST beep codes from it (may need to hook up a speaker to the header on the board itself)?

author: rthorntn
author_rank: Frequent Contributor
timestamp: November 27, 2018, 03:50:24 am
content: Thanks all.Bearing in mind that I'm a beginner, could somebody please expand on how to find out which MOSFETS supply which voltages and how to check their outputs (using the attached image), I do have a Rigol scope here but I have hardly ever used it?Is it the stuff to the right of the CPUs, the 10 x R47 inductors, 20 x LR7843 N-Channel Power MOSFETs and 10 x LR7821 HEXFET power MOSFETs, 5 x R47, 10 x LR7843 and 5 x LR7821 per processor?I guess the VRM circuitry is fed 12v and it outputs voltage between 0.850V-1.3500V (at 10x the amps) for the CPU, can someone please help me understand this?I don't have another motherboard but I have four (used) L5420 CPU's and none of them work.The motherboard sat for weeks while I was waiting for the copper shims.I tried clearing the BIOS.The video is inbuilt.The processor is not getting warm, I have a FLIR. The southbridge on the other hand gets very hot.When I first populated the motherboard I had no idea there was a space between the CPU and the heatsink and so I installed both processors, probably damaging both power sections.Joseph is it Reptronix Academy?The motherboard has a speaker, no beeps. I also have one of those BIOS "error code" PCI cards, that does nothing.I'm pretty experienced with PC building but sometimes you just mess up, the board was NOS and only $150 so if I have killed it, so be it. (the four processors and sticks of RAM were used and were very inexpensive).

author: nsrmagazin
author_rank: Regular Contributor
timestamp: December 03, 2018, 01:52:58 pm
content: If it gets hot, its ok.The ones that do not get hot at all are not ok.Not knowing that there was a space between the heatsink and CPU means you are not experienced. This is also the reason why you sometimes fail.If the power supply is burned, the processors will not have a power input on the power pins. Try to check with a multimeter and the datasheet of the CPU.

author: bitman
author_rank: Unknown
timestamp: December 03, 2018, 05:42:18 pm
content: I've assembled computers/PCs and large rack systems for 30-some years. All the equipment I run today are self-built. In that time I've done my bit of damage to parts - but I've NEVER had to solder/replace components already soldered to the motherboard. PSUs on the other hand go bad _often_ - so I have a simple PSU tester I always use to make sure all the +3.3v, +5v, +12v, GND and other wires (we used to have a -5V too) are correct from the PSU. Motherboards/systems will either go dark or behave VERY strangely if the PSU is out of whack. Heck - at times I just replace the PSU to be sure if I know it's getting old. This is why I have a few PSUs sitting unconnected too - these suckers _will_ go bad eventually, in particular if you like me run the systems 24/7.If this is the first time you're assembling your computer yourself (welcome to the club!), be aware that even small mistakes can be costly. Depending on your CPU and socket brand, just a slight out of balance or worse direction of the CPU in the socket can bend leads resulting potentially in loss of CPU and/or motherboard. Close inspection of the leads in the socket (you may need a microscope) to detect if any are bend can be needed (it is possible to fix that but it requires a steady hand, micro-scope and some small utilities to access individual connectors). If you can, test the CPU in a different motherboard to isolate the issue. Another thing that can go wrong is _not_ grounding yourself as you handle the components like motherboard, CPU, RAM etc. - some homes have a lot of electrostatic "stuff" around, dry interior etc. makes sparks fly simply by walking. This is DEADLY to a component containing billions of transistors. And don't use those that aren't attached to a wire just in case they still sell those on Ebay. Once exposed a component/board may be totally useless or at least it can be hard/difficult to identity the components damaged let alone find replacements for them.When you first get started on an unknown board/cpu - start out simple. Don't plug any cards in, use the internal VGA (most boards today provides some kind of video out) and be sure you have the board status connected to a speaker and some boards have 7segment displays or some color LEDs that indicate POST status. With _just_ the CPU in the socket and connected properly, you should receive beeps on boot that RAM is missing - but that's a good indication that everything is so-far working. Then you insert as little RAM as possible (pay close attention to your manual - some CPUs require the memory to be banked in pairs) and when you do POST now you can now access the BIOS. This will allow you to run hardware tests, validate connections of fans and other external connections you may need/want to your case. Still, no external PCI cards at this point. With a successful BIOS that sees fans etc. insert/connect HDDs/SSDs and all the USB lines - and yet again, a POST will allow you to test that the devices are seen - plug in a boot USB to be sure the port is seen and can be used. At this time, I would add any PCI card I have, again verify that the BIOS can see them, and then close the case and do the OS install.Mounting your motherboard in the computer should these days be less troublesome but with all electronics, you have to take care not to damage it. Be sure it's grounded properly to the case and your offset holders are at the correct height (if not, you can crack the motherboard PCB and trust me, those errors are REALLY hard to find!). With new cases they provide you with the offsets - if you have to purchase them it's really important you get the right hight for the case you have. And all of the offsets must match the mounting holes in your motherboard. Inserting RAM should then be relatively simple - but I have had motherboards with little support in the RAM area, which means you should only insert RAM before you put the motherboard into the case - having the motherboard bend/buckle as you push the modules into their sockets isn't fun considering some of these suckers are expensive.Not seating memory right usually appears in the BIOS as missing RAM or mis-identified. If the RAM is "old" it may have some corrosion on it, which you need to remove (rubbing alcohol is an excellent way to do this). But you can determine if the CPU works by simply powering up with just the CPU. Note - CPUs today typically require their own 6->8 pin power connector.The secret to my success is breaking down a problem till you isolate to a very narrow scope of areas things could be bad in - or just have one potential area. I start with the PSU always - and work from there. Good luck.

author: moontide
author_rank: Contributor
timestamp: December 04, 2018, 10:51:41 am
content: I think your going too technical.You need to verify what works, then you can isolate what to look at. Lots of things can happen but if you have a processor without a heatsink you have about 90 seconds before you do irreprible harm. 10 seconds for danger zone. That's with a duron 1.2ghz.If your not into extra parts I suggest taking out the CMOS coin battery and letting it sit for days. Come back and flash the CMOS again if no post.Good luck CPU!

author: moontide
author_rank: Contributor
timestamp: December 04, 2018, 10:54:48 am
content: Crap, I read it again.....I don't trust your new CPU. I've burned CPUs before. They tend to be the first to go

author: moontide
author_rank: Contributor
timestamp: December 04, 2018, 11:10:51 am
content: 1- check caps for bursting.2- single CPU always goes in slot 0.3- cycle ram in pairs in lowest memory location if duel socket4-dont have CD, HDD or non essential components connected at any time.5-cmos jumper is your friend6-verify parts when possible7- look for damage8- 750w sounds new, board sound old. Verify correct power supply pinout.9-use different PSU power cable.... Seriously I've seen this...Perhaps more when I'm sober....

author: nsrmagazin
author_rank: Regular Contributor
timestamp: December 04, 2018, 01:31:24 pm
content: The MOS has 3 pins. Gate, source, drain.Do you know how to use a multimeter?If you do, then you have to put the multimeter between the gate(+, red wire) and source(-, black wire) and select the proper option on the multimeter. What are the option that you have? Do you have a connection option which beeps when there is a connection?

author: nickeevblog10
author_rank: Contributor
timestamp: December 05, 2018, 01:00:20 am
content: How unusual.Leaving all power disconnected(include motherboard battery) for up to two weeks and Lan Party motherboard comes back to life and stay alive ?! and changing the cmos battery to a Energizer battery works too.I never got a dead motherboard to work

author: Wan Huang Luo
author_rank: Regular Contributor
timestamp: December 05, 2018, 01:56:04 am
content: Quote from: nsrmagazin on December 03, 2018, 01:52:58 pmi have had a processor get really nice and warm when it was indeed rooted for one reason or another. Simply getting warm is not an indication of the processor’s health in my experience.

author: nickeevblog10
author_rank: Contributor
timestamp: May 28, 2019, 11:35:22 pm
content: Sometimes too a motherboard has not booted unless a system fan is connected to the motherboard - this happened once!*pretty sure I know how you feel about this.

author: Housedad
author_rank: Frequent Contributor
timestamp: May 29, 2019, 03:47:56 am
content: Bad caps on the older board maybe. The X7DB8 is from 2008. Right during the time of crappy caps on the market.