Computer Shuts Off But Not Overheated

[bg6051]

Anyone who could help I would greatly appreciate it!

I recently bought an ACER AST180-UA381B.
I run Windows Vista and it originally came with 1 GB of DDR2 RAM
The computer is expandable up to 4 GB, so I went to the local best buy and purchased 3 Giga Bytes of RAM. I removed the original 1 GB and put in just 2 GB.

When using the computer for an hour or so, it will shut down. As I try to restart it will work for about 10-15 min. Then it will shut down again, then for only about 5 min. Eventually it won't run. I have to let it sit for several hours to get back up to the 1 hour. I have let it sit in the BIOS menu and watched the temperature and it never rose more than 38 Degrees Celsius. I understand this can either be a power supply issue or a RAM issue, however I do not know how to dianose this and/or fix this. Can anyone help with any other suggestions as well? Thank you!

[Dias de verano]

Could be the new RAM overheating I guess. The BIOS temp display is only for the CPU I think. Or it could be faulty in some other way, like one or both modules not seated properly. It is simple to check if the RAM is causing the problem. Remove the new RAM, put the original RAM back, run the PC, see if the problem goes away. Did you get cheap RAM or RAM guaranteed to be compatible with your system?

[coolbossov]

Try windows vista memory test (better then nothing

http://www.howtogeek.com/howto/windows-vista/test-your-computers-memory-using-windows-vista-memory-diagnostic-tool/

[Spoiler]

You could also put back in your old RAM and run it. If it doesn't shut down that that would tell you that you have some bad RAM.