Computer can seem to stay on after new power supply

[gorozco]

I just got a 750 watt power supply installed it and the computer can seem to stay on for more than about 40 min or less. The computer worked fine with a okia 500 watt power supply and only 18a on 12v. The 750 watts is fromm alienware but the label says Newton Power ltd MODEL: N750E-00. 750 watt max +12VA 18A, +12VB 18A, +12VC 18A, +12VD 16A, +5V 16A, -12V .2A, +3.3 30A, +5VFP 3A

Computer Specs

AMD Phenom 9750
asus 9600 gso 384mb overclocked
liteon dvd writer
western digital 750gb
Viva VGA/CPU Liquid Cooling System for video card only
motherboard 7050m
COOLER MASTER GeminII cpu heatink
4 antec tricool 120mm

It has 4 pci-e connectors 2 on each line coming from the power supply. I acant figure out what is going wrong. Im thinking the power supply is defective. Can you guys help me out thanks.

 

[Onus]

What are your temps? Is anything overclocked? Reset BIOS to defaults. Reset any overclock to stock. Is that a micro board? Maybe its chipset needs better cooling.

 

[gorozco]

Motherboard is ECS 7050M-M V2.0
case temp about 39c
cpu temp 19c
gpu 43 c
the video card is factory overclocked other than that everything is normal. I didn't have these problems with a 500 watt okia power supply.