occasional continous restarts and bsod on installing windows 7

[SgtNat]

I replaced the motherboard and memory after failure and i upgraded my hdd. Now on occasion my computer screen goes idle and the computer just continuously reboots until i hold down the power button while its on for a few seconds. after unplugging the psu for awhile it generally comes out of this for a bit. possible the psu is bad?

When its not doing that i tried to install windows seven four times. the first two times it gave me a bsod i didn't get the codes for them. the third time it locked up on windows is loading files and the fourth it locked up after it loaded the files and went into the constant restarting.

Troubleshooting: i have ran memtest and it passed 2 no errors with both sticks in.

System specs:
GIGABYTE GA-P43-ES3G LGA 775 Intel P43 ATX
G.SKILL PI Black 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit
Western Digital Caviar Blue WD6400AAKS 640GB 7200 RPM 16MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive
LITE-ON Combo Black SATA Model DH-52C2S-04
PC Power and Cooling S75QB 750W ATX12V / EPS12V
VisionTek 900244 Radeon HD 4870 512MB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready
Intel Core 2 Quad Q6600 Kentsfield 2.4GHz LGA 775 Quad-Core Processor BX80562Q6600
windows 7 64 bit professional

any help would be greatly apriceated. thank you in advance.

 

[MindoverMaster]

Yeah, I would say PSU.

 

[SgtNat]

ya but my only thing is will that also be causing my bsod on installing?

 

[Peter.Cort]

yeah a bad psu can cause bsod's so i'd check it out, if you've got another PSU laying around or can borrow a friends test it out, and PC power and cooling generally has a really good reputation for customer service so you should see if you can get it replaced.

 

[SgtNat]

ah wasent sure i think i can get another psu to try to just get it to run. its still under warrenty so they should hopefully replace it might of been bad from the begging and fried my mobo and memory. thanks for all the help.