Rebuilt PC with random BSOD occurrences

Ok, I ran the Intel Burn Test in standard, high and very high mode. No error. See the temperature results in the attached screenshot.

Works well now for over one day. A forum member gave me a simple but probably correct tip: all I had to do was to raise VCORE in the BIOS by 0,050 V - problem solved. No worker fails and Windows 7 works.

Premature enjoyment, the PC is dead (for now). While it was on, everything worked fine: restart, hibernate, sleep, wake on LAN. This is what I did, in that order:

shut down
detached monitor, ethernet, mouse and keyboard
switched off PSU
detached power cable
screwed on side of the case
carefully carried the PC back to its place
attached power cable
switched on PSU
attached monitor, ethernet, mouse and keyboard
pressed "on" button on PC

Result: black screen, no POST, VGA_LED constantly lit, Q-Code 9A. When switched off by pressing the power button for four seconds, both USB keyboard LEDs remain lit. Now mostly Q-Code 9A (USB initialisation started), sometimes 0E (microcode not found). No change when monitor, ethernet, mouse and keyboard are connected or not. Same result. Occasionally, when using the reset button, I get Q-Code B2 (legacy option ROM initialisation) as an "alternative" with a blinking cursor top left.

What is going on? I am very puzzled. Obviously, the switching off and unplugging of the power cord did something. What can I do now?

Ok. Tried another new disk with OS: 9A. Tried the graphics card in another PC: 9A. Tried again swapping RAM and slots: 9A. I am right back to where the whole mess started in December after reactivating the PCs - but even worse.

To me, this looks like a new fatherboard for each and maybe even new silicon. Still - how can these things go bad in the first place, if not used and disconnected from the mains for half a year? Technology is bad to me : (

Before I order new cousinboards - anyone has a last ditch idea what the constant 9A Q-Code could mean? I seriously hope it is the daughterboards, otherwise, the last option then would be to buy new silicon - ouch!

Back to square one, once again: I finally found a RAM DIMM from another PC which I fitted like so: | void | void | void | void | CPU | void | 4GB | void | void | With that, I get to the ASUS EZ-Mode BIOS setup screen again, select the SSD, and boot.

But now: what to do? Should I go to the Kingston website and select new 4x4GB or 2x8GB memory from their list pertaining to the ASUS P9X79, order and fit that? ASUS' own RAM QVL is still from 2011. Or - is there something else apart from getting new RAM I should try first? Test the CPU once again with the Intel Burn Test? Run prime95 for a day?

What I also don't understand is that the VGA_LED lights up and 9A shows some USB status - rather, with after two years now faulty RAM, I would expect the DRAM_LED to light up? Very confusing for non-technical users, these motherboards.

Well, yes, memtest86+ found no errors after many passes. After everything worked but then (after removing power to re-assemble the PC and put it back) got stuck at Q-Code 9A with the VGA_LED constantly on, no matter what I tried (swapping graphics cards, PSUs, HDDs with OS, Linux USB-sticks), I did not want to order new motherboards and processors for the PCs just yet, that would be very costly, compared to buying new RAM, for example.

So, I took another PC out of service, removed one of its obviously functioning DIMMs, and tried, if the bricked PCs can go at least as far as the BIOS and maybe even boot. And that worked. So, now I am back to square one - but I now know that the graphics card, PSU or HDD are likely not the culprit (because they worked in other PCs).

To me, it looks like I either buy new RAM as recommended by Kingston for the P9X79, or I find out what the "real" problem is, or I buy new motherboards, or I buy new CPUs ... unless you have other suggestions from your experience; I am happy to try other things. I am a regular PC user, not a pro, after all.

I bought new Jamaican RAM. Cheapest option of the three. Let's see how that goes.