P45 Diamond Constantly Freezes Or Restarts

Question

I've build up my system this weekend and everything is powering up nicely with no beeps, CPU running at a good temp, drives are detected in BIOS. However my system at some points contantly freezes or restarts. I use Vista x64. I experience similar results with clean version of XP in x86 & x64 versions. I've tested the GPU, PSU, & HDD and everything works fine but I'm still worried it may be a hardware problem of sorts. I've updated BIOS, clear CMOS a few times, but system still freezes.
1.Vista & XP freeze randomly in 1-5 minutes, sometimes restarts, or simply shuts down & I can't power it up again until I reset motherboard
2. The Memtest86+ V2.0 doesn't find any problem
My configuration:
MB: P45 Diamond
Memory: CORSAIR DHX 2048Mb 1600Mhz KIT cl9 2 x
CPU: Intel Quad Q9550
GPU: N280GTX-T2D1G-OC
HDD: WD Velociraptor

Answer 1

Hello Urk,
what is your current BIOS-Version?
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CPU: Intel Quad Q9550
Which one:
Q9550, C1 (95W)....sSpec Nummer = SLAWQ [supported since BIOS Version 1.0]
Q9550, E0 (65W)....sSpec Nummer = SLACQ [supported since BIOS Verssion 1.3]
You can check the sSpec Number on the CPU itself or on the Intel sticker on the CPU box:
Quote
2. The Memtest86+ V2.0 doesn't find any problem
How long did you run Memtest86+?  Did each of the ten different test run at least once without errors?
Quote
Memory: CORSAIR DHX 2048Mb 1600Mhz KIT cl9 2 x
Test with each memory module seperately.  Clear CMOS with main A/C power cable removed from PSU, load Optimized Defaults in BIOS and test with the following settings:
FSB Frequency = 333 MHz
FSB/DRAM Ratio = 1:1.6 [->> DDR3-1066]
Memory Voltage/DRAM Voltage = 1.6V
Spread Spectrum = Disabled
Auto Disable DRAM/PCI Frequ. = Disabled
Quote
CPU: Intel Quad Q9550
GPU: N280GTX-T2D1G-OC
HDD: WD Velociraptor
What PSU are you using? 
-Brand?
-Model Name?
-Amperage limits (A) on all main voltage rails (12V, 5V and 3.3V)?