HP pavilion elite m9500y power supply

[StupidPC]

Hi, 

I have a HP pavilion elite m9500y.

below is the link for the specification.

http://h20564.www2.hp.com/hpsc/doc/public/display?docId=c01616194

Suddenlty, it won't start with black screen. 

After turning of the power, I can hear no sound from the computer.

My keyboard doesn't work. So, I cannot access any to my pc.

I have checked memory cards and replaced the battery for mother board. 

Nothing has happened. 

So, I am guessing that power supply is the problem.

I am wondering what PSU I should buy.

It requres 350W psu.  I am not sure it is okay to replace with higher W psu, such as 450W or 500W.

So, here are my questions.

1. what is the problem of my computer?

2. If the PSU is the problem, should I replace with 350W psu or higher W for the future?

3. If I want up grade my pc in the future, what would be the best options?

I am looking forward to hearing your advices.

[wb2001]

Here is the standard help file for PSU's. I'd also suggest re-seating the RAM modules. Let's check these before you leap into another PSU.

[StupidPC]

Thanks for your answer. I already checked reseating the RAM. It didn't work.

[wb2001 · Accepted solution]

With the case open, and observing the CPU and rearr case fan, try the suggested PSU troubleshooter.  What happens? If you decide to replace the PSU, I would suggest the Corsair CX600W. The system will only draw what it needs, and you'll have PSU that is quieter and more efficient.  If no upgrades (GPU) are ever planned, the Corsair CX500 is on sale.