I find this a little bizarre - my PC will run for hours on end playing games. Mostly Car Racing Simulators, so quite intensive resource-wise (Although obviously a majority of the load is shifted to the Graphics Card) but when I use Video conversion, the machine will often just reboot without warning.
It even happened to me yesterday when running my own program. It is a variation on a Prime-number generator that I wrote when I was at school over 30 years ago, which I use often as benchmark test, but this time as an exercise in Multi-threading. According to the task-manager, it was running at about 50% CPU load - which as it is a multi-threaded program, means that 1 core is running at 100%.
It is quite an old 3.4Ghz P4 (Prescott ?), the CPU Fan is working, and on one reboot, I checked, and was showing about 40C+ as the temperature, and I have two case fans as well, so cooling shouldn't be an issue.
I had some issues with memory when I was first given the machine, but the 1 x 1Gb Stick I have has been tested several times. The BIOS has been updated to the latest version as have been the Graphics drivers.
The PSU was taken out of a new case that the Mobo wouldn't work in, and has therefore been running for about 2 months now - about 500W if memory serves - and as I have been able to play games for ages, it seems unlikely to be that.
Also, just to clarify, the Video conversion has been using 3 different programs, so it isn't a Software issue.
However, I vaguely recall my Sister - the previous owner of this machine - had some issues, and reseated the CPU, heatsink fan, and therefore could it just be something to do with the Thermal paste ? I'm stumped !
what the temperature when it is running the video conversion or prime-number generator? checking the temperature after a reboot is not going to tell you anything at all.
Sorry for the delay in replying, not had time to check this out properly. Anyway, I have done some testing today, and the highest CPU temperature I have found was 57C during a video conversion. This particular conversion completed, but was a relatively small file... A later test it was about the same temperature, but I didn't see how high it actually was when the PC froze.
57C doesn't seem that high to me, and what I have seen, it is well within the extremes that the P4 will operate under.
Also, I am doing another test currently. The source file is on a USB hard-drive connected to a netbook. In other words, the PC is accessing the file remotely via Wi-Fi and my Router, and this appears to slow it down sufficiently to keep it going. Thus far a maximum of 54C, but still keeping below 50C at times.