System shutting down semi-randomly, fans still running

Trebyna

Honorable
Mar 17, 2013
2
0
10,510
Dear community,

I have a strange problem with my PC and although I'm not a total noob and my boyfriend is working in IT-support we can't seem to figure out the cause.

A few weeks ago my System started shutting down on me. When it happens my monitors turn off (no signal) but I can still hear the fans in the casing running. I checked and all the fans kept running. The computer also doesn't start again by simply pressing the start button, it also does not react to the reset button. Most of the times (but not all) I need to press the start button for a couple seconds, then it starts up again. Other times it takes approx. 10 seconds and then restarts by itself.

What I also observed is, that sometime (but not everytime) the BIOS takes "extremely" long to start up. Normally I just see the BIOS "Start-up-Screen" for the fraction of a second. In some cases it stays on screen for up to 30 seconds.

The error is semi-random. I first encountered it playing SW:ToR where could raid just fine for 4 hours straight but another evening i would shut down on me 5 times in a row. Then I started playing Mass Effect 3 again. Wat happened here was interessting to say the least. I could play just fine for some hours but when talking to my companions my system shut down. It did not happen in all conversations only in some and mostly not more the two times.

Then I found one conversation which ALWAYS lead to system shut-down (that's why I stated semi-randomly in the thread title). I now had a way to test components for failure so here's what I already tested:

- I installed the game onto another HD - error persisted
- I tested every single one of my RAM in every different slot of the MoBo - no change
- I checked temperature of the HDs, CPU and GPU - all fine, error still there
- Checked the load on the GPU – shut down at 30%, no shut down in a different game at 90%
- I traded my GPU for my boyfriends - also no hit
- I did a fresh install of Windows and in the process changed from Win7 to Win8 - error still there
- Turning down the graphics in this particular conversation lead to the error not occurring, but since I’m quite sure I can rule out the GPU I do not really see how that helps me in finding the culprit

Now comes another interesting part of the problem: After the fresh install I first tried to load the save game giving me problems – worked like a charm. Then I continued to install drivers for mouse (Roccat Kone [+]) and keyboard (Logitech G510) – and BAM there it was again. I uninstalled the mouse driver again and it worked again. At this point I thought I found the culprit. BUT: after 2 days of playing with no problem whatsoever it happen again today. Once again it seems to be one specific companion conversation which simply won’t work.

Additional random stuff: One out of three times when restarting either my keyboard or my mouse won’t work. They work again if I replug them to another USB-Port. Sometimes when I shut down my PC after it restarted I get a blue screen. It shows up fairly late (as in: normally shut down of windows should have worked fine) and is only visible for a split-second. I never managed to read the error code.

Since I don’t have a spare PSU and replacing my MoBo would mean also replacing my CPU AND I am not particularly wealthy at the moment I would really appreciate your thoughts on the topic! I would hate to have to buy hardware and then find out the error lies somewhere else!

My specs (home-built system):
OS: Win 8
Motherboard: Asus M4A87TD Evo
GPU: XFX Radeon HD 6870
CPU: AMD Phenom X6 1055T
RAM: 2x 4GB and 2x 2GB Corsair XMS3
PSU: Corsair 400W CMPSU-400CX

I would appreciate any help you can give!
 

Trebyna

Honorable
Mar 17, 2013
2
0
10,510
Thanks to all of you. I will go get myself a new PSU today and then hopefully I'll be able to report the problem solved!

Just out of curiosity: Can any of you tell me how it is possible that an underpowered PSU is able to power the GPU at 90% load but shuts down on me at 30% load? I just can't seem to wrap my head around that. Is it a spike in power consumption randomly occuring (or in my case occuring just in some cinematics) or am I overestimating the power draw of the GPU (I was guessing that the GPU is one main, if not THE main contributor to the overall power draw of the system - it sounds like I am wrong on that)? Sorry for what I fear is probably a dumb question!
 


On a normal home build the GPU is the main draw followed by the CPU and then the rest. If you have a faulty supply as we are guessing is the issue, it could be bad on the 3.3V , 5V, 12V, one rail of the 12V or any combination of the previous. It also may work fine for 20 mins one time and fail in 3 the next then back to 20 the next. Part of the trouble of troubleshooting is that unpredictable nature. When a power supply starts to fail if it is a good brand it will shut itself down. That is what appears to be happening in your case. It may be a factor of total load or it may just be how long that part in the power supply took to get out of tolerance on that cycle. Whatever the reason, a failing power supply is dangerous to the rest of your computer and should be replaced soon.

I can't say for sure why yours is failing in that matter but it definitely fits the profile of a failing power supply.