New build - Keyboard,mouse and screen power problems

[Laurence2010]

hi, this is my first build:

antec 300 case
CiT(or cic, logo is confusing) 750w psu
gigabyte p43 gs3g motherboard
sapphire 4670hd ati radeon
intel core 2 quad q8300 2.5ghz
seagate 500gb barracuda hard drive
2gb ddr2 ram
Windows 7 32bit(not yet installed)

My Computer starts up and all the fans work. but when it gets into the motherboard logo bit where you choose to go into bios and stuff (maybe before this i cant tell), the screen, mouse and keyboard all lose power at the same time and the mouse and monitor power up again but the keyboard doesnt.(tried ps2 and usb keyboard)when i first put it together the keyboard worked for a little while and i could get into the bios and only browse for a little while before the pc hangs and i have to reboot. i cant install os because when i leave the pc and it passes the logo screen, and it passes the black screen with white writing, the computer reads the windows disk and starts to run it. it comes up with a short loading bar but freezes before it finished (noticibly around the same length of time until the bios would crash). i tried stripping my pc down to the basics,(to see if power was issue(still might be?))tried ram in different slots, tried 1 stick of ram.i got a new massive heatsink because i thought the hanging could be due to proccesor overheat(unfortunatley never found out because after i put the new heatsink in the keyboard wouldnt work at all(made me think that the new heatsink drew more power and less got to keyboard.)which meant i couldnt get into bios and see the new temp) i sent back the motherboard and got a replacment.

im still at a complete loss as too what is causing the monitor, keyboard and mouse to lose power at the same time. im thinking about also returning my psu for a replacement (most probably my next step) and was wandering if any of you guys had any ideas of what it could be.

If ive missed anything out you need to know just ask and any help at all is welcome.

 

[COLGeek]

First, if the PSU is ok, then it is more than powerful enough to run your system (even with the massive heatsink). Still I would recommend a better PSU, like an Antec or Corsair. Will cost more, but you get what you pay for.

Let me get this straight, the system makes it up to the BIOS splash screen and then "dies" a little, with the keyboard, mouse, and display becoming non-responsive, but then the monitor comes back to life. Is that correct?

Try this. Remove the video card and any other devices you may have plugged into the mobo (power off first, please). Then connect your monitor to the on-board video. With only the monitor, keyboard, and mouse attached, go into the BIOS and set to its default configuration, save and exit. Try to install your OS.

If successful, then power down and add back your video card and other devices to the mix. The idea is to minimze the variables that may be causing your problem.

I, too, suspect the PSU. Good luck!

 

[Laurence2010]

Ok thank you for your help a second opinions always good!

I tried to do what you said but still no luck, i will continue to get a replacement psu and hope it solves the problems.

Ill write if it solves the problem. And again thanks for the help.

 

[COLGeek]

Good luck!