I have (had) BIOSTAR G41D3C mobo from AliExpress and found it only supports 775 CPUs with TDP of 95W max, so I stuck C2Q 9650 into it and wanted to build compact retrogaming desktop for lan parties with friends. I kept test-booting it as I continued the build, because I really utilized the boards IO and wanted to make sure it works. Finally I boot into XP install, and as it goes along I hear a very loud pop, but PC keeps running fine. So I cut power and look inside, I can’t see anything, but the smell of some powder is noticeable. So the moron in me keeps poking around and I eventually see nothing wrong with the PSU and don’t care about the HW too much so I plug it in and boot it up. It works fine for another like 5 minutes and then another, even larger pop occurs. At this point I cut power, put the thing outdoors, let it be and later I took it apart. Looks like two caps next to CPU have decided not to identify as caps anymore (pics attached).
Can I somehow from these pictures narrow down why has the board decided to detonate itself?
I should add - I also had AliExpress USB3 header to USB2 header conversion cable, USB-C header to USB2 header conversion cable, speaker (yes, the beeper) attached, SATA SSD (also AliExpress sourced), two PWM fans, one of which being part of AIO CPU cooler. The 4pin CPU cable is a cablemod sourced one, so was the 24pin ATX cable I had. I double checked I ordered correct cables for my EVGA PSU.
Low quality caps, most likely. The fact the board booted and essentially worked until the caps gave up means power routing is OK. That means your other components are probably OK as well. I’m not giving you a high chance of success, but launch a warranty claim with Aliexpress for the defective board.
This all makes sense, I know the board is low quality and won’t be opening warranty claim in AE (I had the board for like 5 months and only got to do the build today). I have another board ready but I’m just fishing here for advice that maybe the CPU used here was too much for this board. I have a Q9400 on standby here so maybe I’ll try that. I only used this board because it’s the smallest 775 board I found and nothing else fits into this super tiny case I have. If I want to use any reputable brand for ITX size, I have to adopt 1150 and I wanted to avoid that.
Update: I think the PCIE port is not even running in PCIEx16 mode, meaning maybe this board is not meant to be used with GPU like this and if the GPU tried drawing 75W from the socket, maybe that was not intended use/scenario and maybe that’s why it detonated?
I don’t see that it needs any more reasoning to explain other than it’s cheap, it’s more interesting it still turned on after the first pop. It stands to reason the second became overloaded following, quite literally.
You could replace the caps.
Slow motion capture of this kind of thing:
https ://youtu.be/6WUxgmMDts4?t=216
Provided there was no short (which looks unliekly) it makes sense that it was able to power on again. The 2nd cap would have failed also for the same reason as the first one. Cap’s do not get “overloaded” unless they were run at a higher voltage then they are rated for. Since they have been working fine for years tells me this is not the case.
I agree with @Dutch_Master, everything is OK, just the caps were of poor quality. Likely the electrolyte in them was breaking down through electrolysis causing a high pressure buildup of hydrogen inside the capsule eventually causing a rapid unscheduled disassembly.
Remove the caps, clean the residue you see on the PCB around the affected area using 99% IPA, and install new caps. Be sure to clean it well as the electrolyte is corrosive and will eat metals it comes into contact with.
In your case, anything 270uF that is 16V or higher will suit just fine.
As you have already had two caps fail, and from your pics I can see it seems there are quite a few more of this particular brand, value and voltage, I suggest you replace them all as it’s just a matter of time before more pop.
Do note though that if you are not handy with a soldering iron, this may be quite a difficult task, and even if you are, these specific type of caps can be a pain to desolder and replace, especially on a motherboard which has power and ground planes in it which sink the heat away from the joints. It may work out cheaper to simply replace the failed board.
