Computer shuts down on its own!!!

[Stevenpd]

I have a Pentium D 820 with an Asus P5VDC-MX mobo, 512mb Kingston DDR memory, and im having a lot of computer trouble recently. I began this whole mess after inserting memory in backwards and carelessly powering up. I replaced most of my PC components. Now i have what i just specified above. I originally ran a TR2 Thermaltake PSU but realized after a long time that it was not powerful enough to run my system, which originally solved my first problem which was getting the monitor to display the BIOS settings. I now have a new Rosewill 450W PSU in and it started out running great and got my monitor running with the computer getting my to the BIOS screen but then...the computer shut itself off on its own. I powered on again and then the comptuer shut down on its own after 10-20 seconds of running. I'm getting so upset with this computer stuff because it just isn't working. I'm a beginner with computers building this one as my 2nd for a hobby. (the first one i got up and running) I already tried taking the mobo out of case thinking it was an EMI field or grounding. That wasn't it, and i don't want to keep replacing parts over and over again. I don't know whats wrong. Someone please help me!

~~~Steven Dalvin

[icecube]

Open the computer up and look at the CPU fan when you turn the system on. Is the fan turning? make sure that the CPU fan is plugged into the plug that says CPU fan. Its printed small. Check also to make sure the fan is firmly seated over the CPU (that can be difficult to get it seated properly). The best way to set up a D is to mount the cpu to the MB, install the fan, and then install the memory. Then mount it into the case. I don't really like the way they package the CPU fan. If you don't detach the fan wire from the first clip, it has a tendency to catch on the fan blade, which might just be your problem.

The other thing I would recommend, is locate the battery, and usually an inch or so away, you will see two pins next to each other with the label cmos or clear cmos. Unplug the system and short a flathead scrrewdrive accross them. This should clear the cmos. This would tell the motherboard to reinitialze its search for the processor speed. It could be set wrong and if so, it would do an emergency shut down.

Just out of curiosity, how were you able to seat the memory in wrong?? It shouldn't fit if you try to insert it backwards. My thinking here, is that the memory sticks are not the right type.

[Stevenpd]

Well, thanks for the reply. I'm going to try clearing the CMOS and making sure the fan is seated correctly. About the memory though...it was real dumb of me. I was in a hurry taking some pictures for a class project of the computer, and i took a few pieces out including the memory. I put the memory back in but didn't secure it, and it was in the wrong way. I powered the PC on a week later and well....i heard some noises and a burning smell and that was it for my computer...hehe. I don't even know what to do with the HD, the mobo, the CPU, all things that were in my system and replaced. For all i know they still work. thanks again for the reply