Previously working build no longer booting/POST

[seeadler2009]

Quick run-down of what happened
The system was working fine Wednesday, played a couple of games, regular shutdown at the end, no issues. Thursday it's not booting anymore, no video signal. The only indication is 5 short beeps upon turning the system on.

History
I'll make this thorough to give you a better background about the whole situation.
The base components of CPU, Motherboard, and RAM have been running flawlessly for the past 5+ years. Earlier this year the components moved into a new case and the CPU received a new cooler (CPU itself was not removed from the socket at any point).
Last weekend a new graphics card was installed. This actually gave me a lot of troubles, which I initially attributed to Windows being Windows but maybe it was an indication of failing components?
On my running Windows 10 installation, I was unable to install the latest Nvidia drivers. The system rebooted during the installation at every attempt (previous AMD drivers had been removed prior). So, in the end, I reinstalled Windows (and also updated the UEFI Bios to the latest version) and successfully managed to install the drivers. That was until a couple normal starts later the Windows UEFI boot ended up corrupted beyond repair. So another reinstall, that install was working fine as described in the run-down above.

Specs
Motherboard: ASRock Z77 extreme4-m 1.80
CPU: Intel i5 3570k (last OC was at 4,6 GHz)
Memory: Corsair Vengeance LP DDR3 4x4 GB 1600 C9
GPU: EVGA GTX 1070 Ti SC (old: Sapphire R9 390)
PSU: bequiet PurePower L8-CM-530W

Troubleshooting steps
Ran through any applicable steps in the troubleshooting checklist and currently have the minimum setup of PSU, motherboard, CPU (8-pin power connector hooked up), RAM, and monitor sitting on my desk. (Not mentioned every time but the CPU, case, and - when installed - GPU fans spin up fine.

■ Attempting to boot with just PSU and CPU hooked up results in the expected 3 long beeps.
■ Adding a stick of RAM results in 5 short beeps. This doesn't change when swapping RAM modules or install location.
■ HDMI cable from the integrated video to the monitor - no change, still 5 beeps/no signal
■ adding the old GPU - no change, still 5 beeps (Power connectors hooked up)
■ swapping old for new GPU - no change, still 5 beeps (Power connectors hooked up)
■ reset CMOS at various points - no change, still 5 beeps

At a loss here. My most likely suspects would be either the motherboard or the CPU. But just dying overnight? What are the chances of it being the PSU?

I sadly don't have access to any spares for PSU, motherboard, or CPU. So simply swapping those out as a test is not an option at the moment.

Any further troubleshooting ideas, hints, anything else more than welcome.
Thank you for taking the time to read this. I probably missed mentioning something, so feel free to ask for any additional info.

 

[cin19]

You may open the case to check the LED error code, here is from the Dr. Debug codes: https://www.asrock.com/support/faq.asp?id=334 Because I can't find the beep codes for your MB.

And in other hand your MB has the AMI bios, I can find the standard AMI beep codes, but it will be not the excatly same. For the 3 long beeps ?, but for the 5 short beeps, it looks like your cpu has problem, because usually when you boot the PC without RAM and boot device, the PC will boot. If it does not boot at all, either the MB or cpu has problem. You can go to local PC shop ask for help or how your friend?
AMI beep codes https://www.lifewire.com/amibios-beep-codes-2624543

 

[seeadler2009]

There's no Dr. Debug on this particular board. This also is an AMI UEFI bios so the beep codes are a bit different. ASRock has a list available: https://www.asrock.com/support/faq.asp?id=286

I have managed to locate the issue. Turns out the 5 short sounding beeps apparently count as long ones and indicate a problem with the video system.
The PCIe slot I was using appears to no longer work. Plugging the graphics card into the other PCIe slot available results in a successful boot.
Confusing for me is why just the internal graphics did not work either.

Additionally, while I am now able to boot into Windows again it is now only seeing half my RAM. The system browser inside the BIOS shows all 4 slots occupied, yet also lists two slots as "none" on the main screen. Windows only lists 8 GB as installed and two slots empty. CPU-Z, on the other hand, is showing all 4 slots occupied, and listing the correct amount of 16GB available.
Swapping the sticks around or removing 1 or 2 does not have any effect on the amount Windows is showing. A maximum of 2 sticks is being recognized.
https://imgur.com/a/R7prNUR

I'm getting the impression this motherboard is failing.

 

[cin19]

Check the cpu socket to see any bent pin or not, also check the cpu to see any burn mark or not too, if the MB has bent pin that will cause the no igpu or other problem.

If there is not bent pin. use the two sticks RAM, try install the chipset driver: https://downloadcenter.intel.com/download/20775/Intel-Chipset-Device-Software-INF-Update-Utility-?product=1145

Also test the RAM with MemTest86 https://www.memtest86.com/download.htm

If you done the test RAM, update the chipset driver, because the MB had the newer BIOS, and the MB does not have bent pin, and MB maybe going to die.

 

[seeadler2009]

Thanks for sticking with me.

New chipset drivers had no effect. I've tested half the RAM now without issues, will run the remaining sticks later.

I'll also be picking up new thermal paste Monday and will then check out the CPU.

I have however come across a post now listing some similar symptoms (only half of the RAM being detected properly, iGPU not working, ...). One additional issue I hadn't even noticed before is that the bios no longer allows for the CPU to be overclocked at all. According to several posts now the issues stem from the "Intel Management Engine" being corrupted. At least on this ASRock board, it appears that the IME section of the bios is not touched during a bios flash. There are however relatively cheap replacement chips available so I will give that a shot and see if it can fix my issues.

 

[jankerson]

5 short beeps points to a CPU error and or failure.