Problem with gpu, cpu or ram? freezes alot now

Hi all, hope someone can help...

I can use my pc normally under most circumstances, but i can only play games for approx 10 min or so...
I have replaced the 2 vid cards in sli mode just recently and it didnt solve the problem ( wanted to udgrade anyways ) and as far as i know, have ample cooling with intake fan,exh fan, side exh fan near vid cards and 3 small fans under the dvd player....the only one i question is the stock cpu fan and heatsink....a small aluminium block with a fan.

the video cards ave temp is 37-38 degrees celsius....until i run a game,,,then is raises to 42-42 deg and my pc freezes after that....then i have to reboot.
I run RivaTuner v2.05 and have watched it freeze like clock work....42-43 deg and stop everytime.

My system has been fine for a couple of years till now...only recently has it played up ( 3 weeks ) but my system has had a few changes....
I was running raid 0+1 with my previous mb but that one had a blowout a year ago and replaced it with A8n-SLI premium running 4 sep hd now...all hard discs had a wipe with new mb, i also upgraded ram to 2gb in total. All this ran fine till now...

I dont overclock

speedfan readings for volts
Vcore: 1.41v
+3.3V: 3.34V
+5V: 4.92V
+12V: 11.90V
-12v: -1.50v
-5v: -8.78v
+5V: 4.81V
VBAT: 3.09V

the hd temps ave 35-40 deg
cpu hovers around 30 deg and goes up to about 45 deg before it freezes....

i ran dxdiag
System Information
------------------
Time of this report: 12/15/2007, 11:25:48
Machine name:
Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_gdr.070227-2254)
Language: English (Regional Setting: English)
System Manufacturer: System manufacturer
System Model: System Product Name
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: AMD Athlon(tm) 64 Processor 3500+, MMX, 3DNow, ~2.4GHz
Memory: 2048MB RAM
Page File: 326MB used, 3613MB available
Windows Dir: E:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)
DX Setup Parameters: Not found
DxDiag Version: 5.03.2600.2180 32bit Unicode

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DxDiag Notes
------------
DirectX Files Tab: No problems found.
Display Tab 1: No problems found.
Sound Tab 1: No problems found.
Music Tab: No problems found.
Input Tab: No problems found.
Network Tab: No problems found.

pls help...or post if you need more info

Try replacing your power supply...

Temperatures for cpu are within normal range, though you wouldn't expect the hard drive to run that hot all the time.
We agree with Tmagic650 that your power supply is a likely suspect. You are demanding a lot of a power supply running a motherboard, CPU, 2 video cards, HDD, 7 fans, and DVD. Any weaknesses will likely show up with what you have.
Perhaps download and run MemTest86 for four hours or seven passes, whichever is longer.
Removing your CPU to clean out and replace the thermal paste, and reseat it, is also due. It would be a good idea to upgrade your CPU heatsink and fan, to at least a Zalman or better.