Hello there, had a strange error occur just today, twice, hope you folks don't mind long posts, I'll try to be as specific as possible! Quick specs first :
Intel core i5 CPU @2.67GHz
Radeon HD 4850 1GB DDR5
Asus p7p55D motherboard
800W coolermaster power supply
2x 24" benq monitor
Antec 900 Case
Computer has been running fine for the last 3 years, no problems, yesterday I got a second 24" monitor , plugged it in, ran fine for around 6 hours yesterday, today I played some Garrys Mod which really should not be stressing the PC too much at all, all of a sudden the computer locks up, sort of. I can't really tell whether windows continues to run or not, both screens display black, the large case fan stops running and I have to turn the power off from the front of the case.
On the first occasion that this problem occurred I tried to turn the PC on straight after, about 3 seconds after turning it on the case fan stopped turning and I noticed an LED on the motherboard which I've found to be labelled " VGA LED." At this point I turned the computer off and left it for about 30 minutes, came back and tried it, again the same error, so I left it for around 2 hours, came back and it booted up completely fine, no problems. Naturally I checked event viewer as soon as I got in, but the only critical error was a BSOD error from when I'd tried to turn the pc on but had to turn it off again , I checked the time at which the error occurred and it didn't correlate with the time at which the system stopped responding (during the game)
On to the second occasion, this occured about 30 minutes ago, again everything was fine, started playing counter strike, again not a graphics intensive game, 40 minutes in and the exact same problem occurred. I got the computer on within 5 minutes this time, although it may have been fluke I'll explain how shortly.
So I've been scratching my head trying to come up with some solutions or at least trying to narrow down my options and identify the problem. It seems it has to be either a motherboard,GPU or power problem. I was thinking it might be the GPU overheating, it runs at 68c while in game and idles around 50-60c which I know is a little high, but I don't see how this is high enough to warrant the GPU shutting itself off, if this is what is happening, again its difficult to tell.
Perhaps then there is a motherboard problem, and the VGA_LED is just a faulty light and the GPU is completely fine, my motherboard is at a cool 25c though so I really dont see how the motherboard is the problem. My logic being, if it is a motherboard issue and it doesn't occur every time and my computer can still get all the way to 40 minutes of gameplay it must be heat related, and since the motherboard is not hot, it cant be that.
So then I thought perhaps it was the PSU, checked all my rails and those are fine too. The only reason I assumed it was perhaps a PSU issue was because the top case fan is to the best of my knowledge not connected in any way to the motherboard, it is connected to a molex adapter which runs straight to the PSU, so I cant see how the fan stopping relates to all of this.
Alright so here's my suggestion, I think its silly though, but perhaps not. It seemed too coincidental that all of this would arise just as I got a second monitor so I tried to determine what might have changed. I have two plugs next to my PC desk, so one plug is used for my power line ethernet adaptor, the other plug connects to a 4 plug adapter, before getting my monitor I had only 3 plugs in this adapter, one for my monitor, one for my PC and one for my stereo. I started to think that perhaps by plugging in a monitor to this adapter I'd reduced the power that was going to my computer and this was causing problems, this seems like an incredibly long stretch and I can't logically anchor any decent reason as to why this would be the reason for any of my problems I'm getting, but as I said earlier, first time I had to wait almost 2 hours for the computer to turn back on, I unplugged the plug from the adapter the second time and that is how I got it to work so quickly the second time. Still doubtful though, like I said, Im almost certain the voltages supplied to the computer were fine even with the second monitor plugged in, to the best of my knowledge.
Just one final input, Im running one monitor with HDMI and the other with VGA until I get another DVI to HDMI adapter. Totally stuck with this one, hopefully I've explained this problem clearly, apologies for any confusing writing its very early in the morning here. Thanks in advance for your help!
Thanks for the reply smorizio, just want to make a quick update. Decided to test your idea so I removed the monitor completely from the house power and my GPU, back to how it was before I added the second monitor, loaded fine, after about 10 minutes of gaming screen went black. This time I decided to wait and see what happened next, as usual the large case fan at the top stopped spinning like every other time, but then the light pattern that occurs ( cpu check lights, memory check led etc) all came on. This only ever happens when I turn on the pc so I believe my pc is actually restarting! The case fan does stop and then start when I turn on my pc even before these errors occured so I believe the case fan may not have anything to do with this problem.
Anyway, after it seemed to go through the boot check it sounded like the pc was rebooting, but there was no signal on the monitor from the gpu, and then the VGA_LED came on, I waited a few seconds more and all of a sudden the GPU fan started to spin really quickly at 100% even with the monitor screen still displaying no signal.
This led me to believe that the card was overheating but it was only at 64-66c when this happened, I've noticed that at this temperature my GPU fan was not running at all by itself, I can manually make it start by using CCC but it did not come on at this temperature on its own... is it perhaps possible that by running two monitors on the GPU I had somehow put too much stress on it or overheated it without realising? I'm really starting to hope that this is all it is because I would have no problem buying a new GPU if I was certain it was the problem, what I'm hoping is that the motherboard is not at fault here, though I cant see how that would be the case because if it was faulty I can't see why the PC would start up in the first place. Any suggestions welcome!
Edit: Also apologies, had a look inside the case today and I've found that its a coolermaster 500W supply not 800W, would like to say though that it has been powering the pc fine for the last few years and it seems like it would be an odd coincidence if the second monitor hadn't had an effect here