computer restart or shutdown by itself

[psjohny]

My original system-
CPU: Pentium4 2.4B
M/B: Gigabyte 8SR533, SIS645 AGP4x
Graphic Card: Geforce4 MX440 64Mb/ Geforce4Ti4600 128Mb / Radeon9600 128Mb
Ram: DDR533 128x1, 512x1
Power Supply: 350w / 300w / 450w
Mouse: A4tech Optical USB
Keyboard: Lamel PS2 (cheap one)

I'm don't know what's wrong with my computer. I had changed every parts of my computer but the system still messed up.
Please help me verify what's the problem.

Here is my story

Day 1- I bought a secondhand GF4Ti4600 128Mb 4x. Able to play games- every games with out a problem.

A week later- My computer got a problem can not boot up only seeing vga bios on screen then frozen, i sent my system for repair (shop).

2 weeks later- The vender sent back M/B to the shop, told that the M/B was swopped but computer still couldn't started up.
The shop suggested that the TI4600 not supported by M/B so that i had to change(buy) a new M/B it was ASUSxxxx can't remember.
New ASUS board installed ready for boot up, again there appeared vga bios on screen then frozen.

I went back to shop changed back to my old 8SR533, the conclusion for problem was my Power supply unit would be damaged so i bought a new one it's 300W
Backed to home able to play few games then system shutdown or restart after few minutes of games. I decided to sell away that TI4600 and bought new Radeon9600.

Everything went fine, system shutdown itself sometime. I thought that Radeon9600 would need more power.
The next morning power failure, i went to shop to claim new PSU told them it was damaged. They swop me new one. I tried games again but systems shutdown/restart often so new PSU450W is bought.

Next day DoomIII released!! (my doom)- Something went wrong RD9600 couldn't get into windows showing loading WindowsXP screen then frozen. I changed to GF4MX, it was successfuly loaded but after a while in any game would shutdown/restart my computer.

I went straight to Local Dealer with my PC suspected that M/B was having problems. New M/B swop, again reached home tried the RD9600 couldn't loaded into windows, GF4MX did but shutdown/restart after running game for few mins.
What I had in mind was that Local Dealer didn't change new M/B for me but just rewraped it.

Next day I went back to Local Dealer with my PC again for swopping a new M/B they tested and told me possible caused of all these might me CPU. I head directy to another Dealer of my CPU which is located near by. They changed a new CPU for me.
I returned home hoped that this would help solve all my problems but it didn't!!. Immediatly I went back to M/B Dealer asked them to change new M/B for me because I had changed major parts of my parts but it still didn't work?.
I got Gigabyte 8SR533-P (with the -P) in returned, it was upgraded... By this M/B i could get my RD9600 into windows and play game for few seconds then shutdown/restart by itself again.
without trying with old GF4MX I went to VGA Dealer for 2nd time swopping of RD9600, well.. they allowed me.
I returned home anxiously tried new VGA, Oh God!! this time I couldn't even run game the system shutdown/restart itself immediatly the 3d(ingame session) started.

What the hell is going on? anyone can suggest me any idea?
FYI: I tried ram test changed a new ram too but that didn't help.
RD9600 was tested (running 3dmark01) everytime before they issued to me.
My GF4MX worked very fine in the first day and my system was very stable and was a good gaming machine before I tried the GF4Ti4600.
I am an experience computer user otherwise moderate for someone, well.. I started to know computer from DOS and Windows 3.11 age.

Thank you for reading my story, also please help me.
Remark: The system had been scanned for virus by Norton Anti virus 2003 with updated def and no virus found.
Before installing every new OS the HDD C:/ is full formatted.

[psjohny]

here-the-conclusion
---+---M/B-----------+VGA---------+-PSU-------+--OS-----Results
---+-----------------+------------+-----------+
1)-+---8sr533--------+4MX---------+-350W------+--XP-----Stable-good-in-games-and-applications.
2)-+-----------------+Ti4600------+-----------+---------Good-in-games-and-applications-(for-only-1-week)
3)-+---8sr533-(2nd)--+------------+-----------+---------Can't-even-get-to-bios.
4)-+---ASUSxxxx------+------------+-----------+---------Can't-even-get-to-bios.
5)-+---8sr533-(2nd)--+Ti4600------+-300w-(new)+---------Working-but-shutdown/restart-by-itself-in-3D.
6)-+-----------------+RD9600-(new)+-----------+---------Games-working-for-1-day,-later-system-restart-itself-during-3D.
7)-+-----------------+------------+-300w-(2nd)+---------System-restart-itself.
8)-+-----------------+------------+-450W-(new)+--XP-(2)-Can't-get-into-windows-after-installed-Catalyst3.2
9)-+---8sr533-(3nd)--+RD9600-(2nd)+-----------+--ME-----Working-but-shutdown/restart-by-itself-in-3D-after-few-secs.
10)+**Change-a-new-CPU+-----------+-----------+---------Working-but-shutdown/restart-by-itself-in-3D-after-few-secs.
---+---8sr533P-(4th)-+------------+-----------+---------Working-but-shutdown/restart-by-itself-in-3D-after-few-secs.
11)+-----------------+RD9600-(3rd)+-----------+--XP-----Working-but-shutdown/restart-by-itself-in-3D-immediatly.
---+-----------------+4MX---------+-----------+---------Working-but-shutdown/restart-by-itself-in-3Dimmediatly.

[pickel]

I'd start from scratch. Assemble the computer with the RAM, video card, CD and hard drive. Boot from CD. I assume you're running XP ??? Boot from the XP CD Rom and re-install the OS, saving your system settings. If that works then add whatever else you have one thing at a time, evaluating the performance.

[psjohny]

I did dissambled put M/B out side my PC case with only ram HDD and without CD Rom. Restarted windows but results were the same.
Have not try install fresh copy of windows I'll try that later.
Am I attacked by virus? Formatting didn't clean virus away?

Johny

[psjohny]

Yes! you're right!
I had been stupid for a long time, never realized that OS might need to reconfigure for hardware changes at least should setup new hardware by adding piece by piece. Thank you.

One more question, seems like my new CPU is not quite stable because it fails in CPU test in 3DMark03 and shutdown my system on some application.
Please for more answer.