How to tell if old PC is a Homebrew? - Page 1
Forum section: electronics / general

author: buck converter
author_rank: Regular Contributor
timestamp: July 12, 2017, 05:42:50 pm
content: I recently took apart an old PC. A few things stuck out makes me think it was a slap job home-brew:The case slid right off, without removing a single screw.The heat sink on the graphics card is held by a single spring post and is not attached. (possibly how this failed)?The CPU Heatsink was rather small compared to other computers I have taken apart. It did not have any thermal paste. Did old CPUs not get as Hot?The power supply had the biggest oddity: The power switch was wired in series with the primary input with thick cables.I thought unplugging a computer was bad.

author: Nusa
author_rank: Super Contributor
timestamp: July 12, 2017, 07:01:53 pm
content: Not nearly enough info to say much. Without context, "old pc" narrows it down to about a 30-year period. You didn't say anything about the origins of the machine...was it ever known to be working in this configuration? You didn't identify the CPU or anything else. No pictures.The earliest generations of PC's had slow CPU's in big packages that didn't require an added heatsink at all.

author: Kevman
author_rank: Regular Contributor
timestamp: July 12, 2017, 07:40:57 pm
content: 1. All that means is that someone removed the screws from the case. Even home-built machines have case screws.2. All that means is that one or more heatsink posts failed. What happens is that the plastic gets brittle from the heat and they let go. Many older GPU heat sinks just used 2 posts on opposite corners.3. No. CPU heatsinks didn't really become a thing until the faster 486s, and CPU fans not really a thing until the Pentium. CPU heatsinks/fans didn't get as big as they are today until the Pentium 4- size increased gradually over time till then.4. All AT computer Power supplies are like that. There's huge differences between the AT and ATX case standard- this is one of them. The presence of a backplate is another- on ATs there's usually only a small hole for the the keyboard connector.I assume what you mean by home-brew is home-built- that someone bought individual motherboard, ram, case, etc and built it. All told none of your observations imply one or the other way.Post a pic of the machine inside and we can tell you a lot more about it. Based off of your observations I'd say you're looking most likely at a (Super) Socket 7 or Pentium 2, but that's just a guess.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 12, 2017, 08:31:56 pm
content: Quote from: buck converter on July 12, 2017, 05:42:50 pmAs others have said, this can describe pretty much anything produced in the past 30 years.Many modern Dell machines can be opened without removing a single screw.Heatsinks on mainstream graphical cards were more common after the year 2000.The importance of thermal paste on CPU heatsinks was ignored for quite some time after they were widely used in the PC market.As said before, AT power supplies are exactly this: power supplies with a clunking switch. These power supplies were mainstream up to around mid 1990s. Ah, don't worry about destroying your computer with that: the AT standard defined a pin called "Power good" that was designed to properly handle this scenario. Obviously that you still needed to "Quit to DOS" from your Windows 2.x/3.x session before powering off your computer, under penalty of having to reinstall it.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: July 12, 2017, 09:17:00 pm
content: Having an actual mains switch, sounds like an AT-style computer. The ATX case and mobo went over to using soft switching. That is quite old then, probably mid 90's at latest. If it's an AT it will also have the larger 'DIN' socket style of round keyboard connector. No mouse socket, if a mouse was used it had to go on the serial port.The early computers ran DOS, and you could just switch them off. Provided you hadn't any unsaved work, of course. Windows brought with it the need for shutting down the OS, and the soft-controlled ATX PSU was essentially a response to that need.The 8086 and 80286 didn't even have a heatsink. 386's typically did, and it was with the 486 that processor fans started appearing.

author: tautech
author_rank: Super Contributor
timestamp: July 12, 2017, 09:33:47 pm
content: Built my own PC's for years and many of these things would/could be found in most of my creations:Unmatched RAMMultiple coloured cable tiesDifferent screws here and there (not matched and assorted from my 'PC screws' jar)Not all screws in drive bays.No OS stickers on the case.

author: Ampera
author_rank: Super Contributor
timestamp: July 12, 2017, 09:53:40 pm
content: Most modern homebrew machines tend to use brand name parts, while OEM machines use OEM parts. For example, it's rare, if not impossible to find something like an A-BIT board inside a Dell/HP machine (Had to use A-BIT as an example because a lot of the motherboard manufacturers today are also pre built machine manufacturers)In the modern day, a small heatsink on a CPU is common for more OEM designs to save costs. (These things are intended to be replaced on contract when they die)I doubt this is anything older than 1998ish because graphics cards did not really have heatsinks before then. I doubt it's anything modern because almost all modern graphics card heatsinks are screwed on with metal screws. Actually even some older cards use screws. Maybe....The power supply is the strangest thing. Pictures would be nice so we can see what you're talking about. Unplugging a computer isn't particularly bad. You're unlikely to damage something physically by doing so. The only risk comes when data is being written to non-volatile memory (hard or solid state drives) and the system looses power. Data corruption isn't possible, especially on systems without a journaling file system (pre NTFS/Ext3). If you were to be running something like DOS where disk access is not a constant thing, unlike on Windows, you don't need to do anything to shut it down. You can just cut the power, normally with a switch attached to the PSU.The dead giveaway for an OEM machine is company branding. There is almost always a Dell, HP, Compaq, etc. badge or decal somewhere on the machine.