Pc randomly restarts

My computer is using vista home premium with sp2, it’s a pre built, I changed the PSU to the cooler master 650w, the case fan , the graphics card from x1550 to 4850, the case fan and add a extra 500g hdd, the changes have been made for 8 months now and there was no problem before.

About a week ago it started to restart it self randomly or freeze, sometimes the blue screen of death comes up most of the time it freeze or restarts.

But when I watch any video file or use a video converter, like winavi MP4 converter it restarts in about 1to 2 mins, sometimes after the restart, when I log in and the start up menu comes up the computer freezes, I tried to restart but the same thing happens until I go to safe mode and use system restore to a few days back.

The restarting and freezing started when I notice the PSU is a little hotter than before and the PSU’s fan at the back seem to have less air flow than before, so I took it out to check for dust and there wasn’t much. When I put it hack in, the problem started.

I’m not 100% sure about this but the fans are not spinning as strong as before, before and after the problem started

I put the x1550 back in, still the same then I put the old PSU back in and still the same. I have tested the 2 1gig ram with memtest86+-2.11.iso 8 passes each and there was no error.

and I tried the stress test by prime95 and it run about 3 tests ( 10 mins) then the computer froze , then I tried it again 4 times and it froze in less than 1 min every time

here is the temps while the test was running

extra hdd - 49

TMPIN0 - 46
TMPIN2 - 49 to 51

ACPI TEMP
THRM -40

CORE 1 - 58
CORE 2 - 58

are these temps normal, and does anyone whats wrong and how to fix this.


Thanks

Its your Power Supply. Get a new one to test with. It operating hotter means something changed, and obviously not for the better. Hopefully its still under warranty. Random reboots and fan issues are almost always the power supply. id bet money on it.