(Wall of text, I tried to fit as much info on the first post as possible )
Hello, two days ago I was gaming just like normal when my computer crashed. Black screen, no sound, I could hear the fans inside speed down a bit. Ok, I reseted the computer from the power switch on the back. When I tried to boot it, it kinda hang in a loop, booting again and again and I couldn't hear the BIOS "everything's okay"-beep. I switched the power off and let it to cool a while. Tried again, this time the boot went fine but it crashed again just after windows had loaded. Now it's been doing that ever since, randomly crashing into a black screen. Sometimes even during the boot before windows loader. A Prime95 Blend stress test also causes the crash after a while. The low RAM usage test seems to run fairly long without crashing (but it could be caused by something else since the computer crashes even when nothing's running)
My setup is the following: (yeah it's a fujitsu-siemens package machine)
AMD Phenom 9500 X4 (Quad-core) @ 2,2 GHz (no overclocking)
2x 2 GB DDR2 at 333 MHz (I think)
(Asus) ATI HD 4850
2x 500 Gb Western Digital hard drives and a DVD-RW drive.
FSP400-60HLN Power supply at 400W. (yeah, I know it sucks)
I bought the graphics card two weeks ago. The one before was Nvidia Geforce 8800 GT, which fried so I had to buy a new one.
So here's what I've tried. I ran Memtest86+ on both of the memory sticks. Weirdly enough the other stick caused Memtest to crash instantly, the other ran fine. When I had both plugged the test crashed after a while. At this point I was sure it was the memory, but the with the working stick the computer still crashed after a while. Then I tried to change the Graphics adapter, I changed it to a 10 year old one (Gainward GeForce 2 or so lol) and Memtest ran fine for several hours with both sticks plugged in. Still, when I used the computer it crashed after a while. Even in safe mode a stress test causes it to crash. Also tried with a friend's (Asus) Nvidia 8800 GT but still the same thing. S.M.A.R.T. analysis of the drives shows no errors, all green. I've also flashed my BIOS to the newest version.
So now after reading forums for a while I'm fairly sure it's the power supply. Since I changed the graphics card I think the new one is using more power that the PSU can handle. So the day before yesterday the load caused something inside the PSU to break and now it's not working properly. The voltages measured with a multimeter seem to be fairly good though. (12.22 V on the 12 V rail) The PSU is a fairly bad one, 400W with two 12V rails at 14A and 15A.
I understood before that the 4850 shouldn't use that much more power that the 8800 I had but it seems that the power usage has fried the PSU. Also the PSU feels really hot when the computer is on.
Normally anyone would go to buy a new power supply on my situation but the thing is that I'm a student and wouldn't want to use money on a new PSU before I'm fairly sure it will fix my problem, especially because I just had to buy a new graphics card.
Is there anything else that might be causing this problem or anything else I could do to find out the cause? Like I said the crashes generate no BSOD and the windows error logs show nothing. I also unplugged the DVD drive but it didn't help.
TLDR Version: My computer keeps crashing to a black screen randomly, could anything else than a bad PSU be causing it?
Everest shows the CPU and motherboard temperatures all being within 40-50 C, and I've cleaned the fans. Haven't tried to check the heatsinks yet but if the sensons aren't broken I think it should be fine. I suppose I could try to borrow a PSU from a friend, he has a Be Quiet! 550W PSU with four 12V rails 18A each.
Ok I tried switching the PSU to the one I mentioned from my friend, and it crashed when I was just about to start Prime95 ... Don't know if it's the processor or the motherboard or what. I'll try to do some driver cleaning to see if that helps. (Don't think so since it ran just fine for two weeks and crashes also outside windows)
Edit: Don't know if this thread should be moved elsewhere, because it seems the PSU is not the problem. (or my friend's PSU is also too weak but I don't think so)
About the power supply I'm not so sure. I though of this:
LC6560GP3 V2.3 (49.90 EUR) http://www.lc-power.de/index.php?id=203&L=1
But they don't have that one either, I'll check out some stores near me some day later next week.