PC does quite odd things

[cpaw]

Hello everyone!
I have bit of a problem with my PC, it works kinda randomly.
When I start it, one of the following can happen:
- boots normally

- hangs on ASRock logo

- hangs on blinking cursor

- powers down just before getting into Windows (after Bitlocker prompt)

 

Sometimes I need several attempts (I think five at most) to start the system. Then I may have no problems whatsoever for some time. Sometimes it boots at every attempt.

Once it boots up, it works nice and stable. I can play games and render video for hours. I think this rules out PSU damage or not sufficient connection between components.
One game however, Hawken, is kinda glitchy: it may hang in the middle of the gameplay, and then either come back just fine, or screen can go black and stay so, or screen can flicker, but only in games, framerate is very low when this happens. I can't rule out that this is just game's fault, as it is in beta for years. To resolve, I can either reboot or turn the GPUs on and off in Windows' Device Manager.

For a few hours, Sony Vegas just ceased to render. It works fine now, but I could have changed something in the configuration.

Here's the setup:
i7-5930K

ASRock X99 EXTREME3

Asus ROG SWIFT PG278Q

Two MSI's 980s
Crucial Ballistix Sport 2x8GB

Cooler Master V1000

TPM module, SSD, two HDDs in RAID0, etc.

Latest NVidia drivers, Windows 10 is updated, so is motherboard's BIOS.

 

Additional observation. Motherboard has audio input, I hook my tablet to it, to pass audio from it, through PC to the headphones. Nice to watch YouTube. When I connect it, screen turns black for half a second. Once, it glitched out, I think I accidentally touched charging port of the tablet with 3.5 mm jack: image was distorted, kinda pixelated (not resolution change), PC worked fine.

 

CPU is overclocked to 4.4 GHz at 1.29 V, but I don't think that's the issue, as it does not crash after hour of Prime95, but at boot time.

Nothing is overheating either.

It is hard to diagnose, because the problem occurs seemingly randomly. I mean, I can swap parts, try one GPU, one RAM stick, etc., but it may take hours for the issue to appear. My main suspect is the GPU, due to flicker, but I am not sure I can RMA it on a hunch.

 

Would love if someone helped me. Thanks for even reading such lenghty post!

[Constantin]

You probably set the buss speed to high, if you did, i think the ram is causing you the problem

[Sack]

-snip-

First, follow your own post when asking for help. Second 1 hour on a benchmark is not long enough to make sure it's stable, and you shouldn't use prime95, I don't remember at what CPU but you can wreck your CPU if you use it the wrong way now.

 

I've had issues with RAM where the computer would stay on fine for 10 mins and crash, and I've not heard of it staying on any longer than that, so I doubt it is the issue. You have nothing to lose by pulling out the suspected GPU and let it stay on, or game waiting for the problem to reappear.

[cpaw]

I only upped the voltage and mutiplier, BCLK is stock. Rebooting to double-check.
Yup, BCLK set to Auto.

I used this CPU overclock for month or so without any problems, this issue appeared recently. Also, shouldn't it crash in Prime95 when load is high, when it crashes at boot time, with low load? (Correct me if I'm wrong; not particularly experienced overclocker here.)
I wanted to avoid this, but I guess I'll take one GPU out. Framerates will be painful.

[cpaw]

Hey, thanks for replies.

I noticed that my headphones are very noisy, and also the noise is different for different GPUs usage. Is this normal, or maybe motherboard and GPU are shorted? Never noticed that before, and it correspond well with external audio source causing the screen to black out.

[cpaw]

Checked some things:
- issue still occurs on default BIOS settings, after resetting CMOS (ain't OC problem then)

- HDDs are not the cause of the problem

- GPUs don't seem to be either, unless I broke two of them - problem may (or may not) occur with any number of cards and PCI-E slot configuration

Next I am going to boot Linux from a flash stick, to rule out TPM module and I'm getting old, but known-good GPU.

Any other ideas? Could it be a bad PSU? One broke on me month or so ago, this is a replacement. But wouldn't it crash on load?