GTX 560 Ti won't work with my RAM anymore

[raveloda]

Strange issue plaguing the computer. I've had this computer working fine for years now. It suddenly stopped booting and would power for just a half-second and then shut off and cycle. I noticed that it rarely would stay on for about 5 seconds running only the fans and then shut off. No onboard speaker to check for codes, unfortunately. :/

I first suspected the RAM, so I pulled and swapped them in combinations with no effect. Trying more thoroughly and suspecting the motherboard, I pulled everything off the MB and started plugging things in one by one. I got the PC to boot again with everything minus the video card. Unfortunately despite things looking good, the problem immediately returned as soon as I added the card. I tried the secondary PCIx16 slot on the MB with no effect. Tried everything from scratch again and it failed, again, as soon as the video card was added.

Through some more troubleshooting I ended up booting it with a single RAM stick + video card and it worked fine and booted to Windows. The single stick looks to have passed mdcheck. The PC also boots with the single second stick, but not with both. I'm at a loss, but at least the PC works with half RAM. No recent hardware changes, upgrades to either software or drivers...

In summary. Known good configuration fails to boot suddenly. Manages to boot with both RAM sticks and no video card, or with video card and either RAM stick.

Bad video card? RAM? Memory slot? PSU undervoltage? Any thoughts?

Windows 10 Pro x64
Intel i5-4670K - no OC
ASRock Z97M Pro4
Seasonic SS-250 PSU
PNY GeForce 560 Ti
2x4GB EVGA DDR3 set (08G-D3-1600-MR) PC3-12800

 

[Barty1884]

Definitely a weird situation, that's for sure.

You have 4 DIMM slots. Each module will work in any configurations without the GPU installed? Is there a specific slot that won't work when the GPU is installed? Or is it a matter of 2x DIMMs = no post?

 

[raveloda]

Definitely a weird situation, that's for sure.

You have 4 DIMM slots. Each module will work in any configurations without the GPU installed? Is there a specific slot that won't work when the GPU is installed? Or is it a matter of 2x DIMMs = no post?

I got memtest as I didn't want to trust the built-in utility. I've ran full tests on both sticks individually and in pairs. So far I can't find errors. It seems to be booting fine on slots 2&4, like you said, but it also passed in 1&3. I didn't think to try it because a previous MB would yell at me if I didn't fill them in ascending order.

I'll keep testing, but I am less inclined to believe it is the RAM. Thank you