I bought this computer bundle the other day
http://www.walmart.com/catalog/product.do?product_id=8195032#Specifications
since the gcard sucks i wanted to buy a 8800gs or gts BUT my power supply for the computer is 250w.
i was thinking to buy a 500w power supply and than just buying the 8800gs
is this possibility that doesn’t have high risk?


if you buy a good quality power supply, then no.
A power supply only draws as much power as the computer needs.
and luckily for you, HP computers tend to be upgrade friendly and use ATX power supplies
no because 500w does not mean it runs at 500w it means if your pc needs it ican run up 500w on full
but even while playing games with a 8800gs your probs not gona used anymore than 420w
If you buy some $30 piece of garbage then you are taking a gamble.
If you buy any decent 500W PSU for $100 or so, you should be good to go. I had a cheap Dynex brand 350W PSU and it lasted me for 3 years being left on constantly. But it was also of poor quality.
I purchased a higher quality PSU this time, a Coolermaster Pro Power 750W and I am pleased.
Plugging in a PSU that has more power than you need won’t do your computer any harm, unless you have poor quality components, which is unlikely.
In short, no, putting a decent 500W PSU into your computer properly and not overloading it will not cause your computer any harm.
I’m with finger