You are probably unable to turn it on, unconnected to a motherboard, 
because it is a switching power supply that delivers power with 
demand, and consequently needs a load in order to work. Plug a fan, 
or a hard drive into it, and then try running it. When you do turn it 
on remember that a ATX PS uses a soft motherboard switch, and will 
need to be hacked to turn on when not connected to the motherboard. 
Take a paper clip, and plug one end into the green wire connecter on 
the motherboard power lead, and the other end into any black wire 
connector, then power it on.

You can not do better then PC Power & Cooling at the high end, or 
Sesonic, another very good PS design at a more reasonable price.
Mark Rode

At 09:42 PM 3/17/2010, you wrote:
>My HP 200 server atx psu is giving me problem. I unable to turn it 
>on but if i fix it to a pc, it work fine. Where is the problem ? 
>Anyone recommendation for good server psu ?
>
>Thank You.
>Chan Fan Chong

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