Inconsistent Restarts. Any advice appreciated.

Hi, as the title reveals I have been getting inconsistent restarts ever since I put together my new computer.

My specs are as follows:

CPU: Intel Pentium D Processor 930
Motherboard: ASUS P5WD2
RAM: OCZ DDR2 2GB (2*1024MB sticks)
GPU: nVIDIA GeForce 7600 GT OC
PSU: 430-Watt (Antec P150)
OS: Windows XP Professional 2002/Service Pack 2

So the inconsistent restarts usually happen when I am running a multi-player FPS application or a video or music. I have suspected it could be my sound or video drivers but I have updated both. I have installed additional fans and all temperatures are normal. I have checked my even log and found that "ATAPI" errors have been occurring. Minidumps can be posted if it will help. Please offer any help to this problem, it would be greatly appreciated.

UPDATE:

Recent BSOD errors:

- DRIVER IRQL NOT LESS OR EQUAL
- STOP: 0x0...8E
- STOP: 0x0...F4
- STOP: 0x0...D1

here are my most recent minidumps. If anyone can help me take a look at these it would be greatly appreciated. Thanks in advance.