PC boots up then powers its self down

Hi im not sure if im the right place to post this but here goes, yesterday i bought myself an AMD 64 x 2 dual core 5600 brand new along with a new tower asus vento and a 250gb sata hard drive dvd burner and a 700w power supply and i already had 2gb of corsair ddr2 ram and a gigabyte GA M59SLI S5 motherboard and a nvidia pcie GFX card (think its an 8 series).

I then proceeded to assemble the parts taking care to read the manuals for the motherboard as i put it together, after i had finished putting it togther, i powered it up and it started fine, but then after 30 seconds or so it just turns its self off like im holding down the on/off switch.

all of the parts were purchased brand new yesterday apart from the MB, GFX card, and RAM all of which were sent to me a couple of weeks ago by my cousin who wusing them in his machine with the same set up and they worked fine.

I checked the PSU wiring to make sure i had connected everything ok and that the on off switches etc etc were wired correctly and as far as i can see its all ok.

there is no operating system on it yet as it wont stay on long enough for me to even get into the bios.

I was wondering if anyone could possibly give me some advice or help??

thanks

 

Could be a sticky power switch. To eliminate, swap with the reset button or remove the power switch and short the power on pins.

Next thing I would try would be a PS if you are getting a BIOS screen before it shuts down.

Other thing I would try is remove everything except the video card. If it still fails, you can remove the video card next and it will complain about no video card but shouldn't shut down on it's own.

After that, you only have the mobo and CPU.

 

Hey thanks alot took it apart piece by piece as advised and was a loose wire from my PSU thanks alot for the responses,