My PC regularly reboots during use

[Derrs]

So I built my PC with some friends about 10 months ago, and I was having no problems with it until about 4 weeks ago.

Problem 1: Now the problem seems to vary slightly from time to time, but it generally revolves around the computer going black screen and then rebooting. Some times instead of a black screen, there will be a coloured screen (pink, blue, green) with vertical lines, and then it reboots. At the beginning, it only ever seemed to occur when I was playing League of Legends, and not when I was playing other more graphic intensive games like Watchdogs or something, however now, it seems to just happen more randomly when I'm not doing anything.

Problem 2: The second problem I have been having over the last two weeks is that when I go to turn on my computer, it will turn on but it won't actually boot up. The monitor says there's no signal detected and the lights on my keyboard don't light up. I've looked inside the case when this has happened and whenever it does happen, the fan for the cpu is always not running. This generally fixes itself after a while and I can finally turn the PC back on.

I've tried solving the problems above myself. For the first one, I believed it was an issue with the RAM. I have two sticks in, and thinking that one may have gone faulty, I took one out, tried out how things went, switched them around, etc. Things went ok for about a week and then the rebooting started happening again. I went through all my drivers and updated everything and I downloaded a couple monitors to see what was happening. WhoCrashed has told me the same thing every time after a reboot:

On Sat 22/11/2014 18:33:48 GMT your computer crashed
crash dump file: C:\Windows\Minidump\112214-15468-01.dmp
This was probably caused by the following module: ntoskrnl.exe (nt+0x5BD991)
Bugcheck code: 0x124 (0x0, 0xFFFFE0008465E038, 0x0, 0x0)
Error: WHEA_UNCORRECTABLE_ERROR
file path: C:\Windows\system32\ntoskrnl.exe
product: Microsoft® Windows® Operating System
company: Microsoft Corporation
description: NT Kernel & System
Bug check description: This bug check indicates that a fatal hardware error has occurred. This bug check uses the error data that is provided by the Windows Hardware Error Architecture (WHEA).
This is likely to be caused by a hardware problem problem. This problem might be caused by a thermal issue.
The crash took place in the Windows kernel. Possibly this problem is caused by another driver that cannot be identified at this time.

I have done stress tests for the GPU and everything seemed fine. I tried to use Memtest86 but for some reason at the moment, my disk drive doesn't seem to want to read the blank disks I'm putting in so I can't try that out right now.

For the second issue I was having, I did a CMOS reset on the motherboard by taking the battery out and I have pulled out and put back on the 4 pin connector cable for the CPU fan.

I'm no computer whizz and I've had to get my friend to help me out quite a lot to help me so far, but what we've both said is that we believe it's all down to the motherboard not working correctly, whether it's the battery, a cable or the whole thing, but we could easily be wrong which is why I'm asking here.

The specs are:

Windows 8.1
Case: Aerocool Xpredator X1
HDD: WD 1 TB
Motherboard: Gigabyte F2A88XM-HD3
CPU: AMD A10 6800K Quad-Core Processor
RAM: Corsair Vengeance 2x4GB DDR3
GPU: Asus Radeon R9 270X (DirectCU II Top)
PSU: Corsair CX500

I use the computer for mainly gaming, browsing the web and autocad.

 

[clutchc]

That can be one of the hardest things to track down. The PSU would be a prime suspect. Defective or under-powered will usually cause that. Be sure your 24 pin and 4/8 pin PSU MB connectors are firmly in place... so that their clips are snapped over the locking tabs. A loose connection can work apart as heat changes.

Try removing the gfx card and running off the integrated video for awhile. See if the issue is still present. That may give us a clue.

 

[Derrs]

Ok, I've pulled out and stuck back in the cables from the PSU - MOBO and I'm now running on the integrated video so I'll give it perhaps a couple of days to see what happens.

 

[clutchc]

Ok, I've pulled out and stuck back in the cables from the PSU - MOBO and I'm now running on the integrated video so I'll give it perhaps a couple of days to see what happens.

I presume the discrete card is removed from the PCIe x16 slot...

 

[Derrs]

Ok, I've pulled out and stuck back in the cables from the PSU - MOBO and I'm now running on the integrated video so I'll give it perhaps a couple of days to see what happens.

I presume the discrete card is removed from the PCIe x16 slot...

Yeh, the gpu is out. Haven't experienced any problems so far anyway. I've been a little busy lately so I haven't been using my pc as much but I'll give it until the weekend to see if anything crops up

 

[Derrs]

That can be one of the hardest things to track down. The PSU would be a prime suspect. Defective or under-powered will usually cause that. Be sure your 24 pin and 4/8 pin PSU MB connectors are firmly in place... so that their clips are snapped over the locking tabs. A loose connection can work apart as heat changes.

Try removing the gfx card and running off the integrated video for awhile. See if the issue is still present. That may give us a clue.

Ok, so since last week when I removed the graphics card, replaced the motherboard battery with another battery, and checked to see if the cables were tightened up, I have experienced none of the problems that I was having before. The only little weird issue I am having though is the clock on my computer doesn't update every time I turn on my pc, it just continues from when I turned off the pc the night before.

Also, as a side note, also kinda strange, the fps I have been getting while playing say League of Legends or War Thunder is pretty much the exact same as when the graphics card was in. In LoL, I am still hitting 110 FPS and I havent turned down any of the in-game graphics. Not sure if this is normal or not, just seemed weird to me.

I am guessing the next step would be to insert the graphics card back in and to see if the problems return?

 

[clutchc]

Now, that IS odd. I'm at a loss as to how you could be getting the same fps with the integrated video as with the discrete card. The integrated is basically a HD 6670. Unless LoL is a really low demand game.
And the clock is another oddity. How is the time/date in BIOS? Does it update normally?
Do you have access to any other discrete card you could try for awhile? If not, yeah... try your 270X back in.