power supply or motherboard problem???

[doesntplaywell]

when I shutdown windows my fans keep running & the power light stays on... I've unplugged everything but the cpu fan & the vga.. hard drive & cd drive
specs are gigabyte 680i sli dq6...corsair 620hx ( if you need more info I will get it...also it's a new build )
any help would be greatly appreciated

[jonnyGURU]

Old Antec power supply?

Seriously.... pull the PSU and try to look inside with a flashlight (or open it up if it's not under warranty still.) Look for swollen caps inside.

[doesntplaywell]

power supply is corsair 620hx... I'm going to reload windows & see if thats the problem
new info that may help....the power supply will shut off with the switch in the back....also if I hold in the power button on the front of my case for about 5 seconds it shuts the fans off.....would this rule out the power supply of being bad???

more update...it's not the psu...been on the phone with gigabyte for several hours.... I'm down to this... it'll shutdown correctly with one 2 gig stick of ram but not both... doesn't matter which stick or which slot...one works - two doesn't