Problem with starting the pc

[Sinister]

Dudes can someone advise what is wrong with my system, I built my rig 9 months ago and has been running sweet untill now

When starting the pc all fans spin but pc does not come on. To get it to run I have to unplug the power cable from the back, then hold the power button for a few sec then plug it all back then she fire's up?

It's annoying I have cleared the cmos removed the battery checked everything what do you think guys.

Rig is running stock it's fast enough, could it be the power supply?

spec below

DFI LanParty UT NF4 Ultra-D
AMD Athlon 64 3700+ San Diego
Western Digital Raptor 74GB
PowerColor ATI Radeon X800 XL 256MB
G.Skill 1GB DDR FF PC4800 (2x512MB) Dual Channel Kit (F1-4800DSU-1GBFF)
Enermax Noisetaker 485W

 

[Sinister]

many thanks for the advice

yep when I unplug the power and then push down on the power button it discharge the power in the system, then the rig fires up.

Have not added anything new just started doing all this Monday

I've unplug all non-essential parts still won't come on unless remove power cable then discharge the rig.

will see if I can get a mate to lend me a psu

 

[Sinister]

just a update guys swapped the psu system fires up as it should

will rma the psu

many thanks for the help these forums are awesome