Gtx 670 in old computer

No problem........
im wondering about the power supply though,

what are u wondering about the power supply? the minimum for gtx670 is 500W. im worried about it.

The power supply make and model. If its a good 500W PSU, it should run it fine. With the i5 you should be alright. Just overclock it a little if you can.

im using Cooler Master eXtreme Power Plus 500W RS-500-PCAR-D3.is okay right? i am planning to buy it gtx 670 first and later i5

If you're running a low end Cooler Master.........it might be a good idea to get something more powrful

You should grab atleast a good 600W PSU. Better above than minimum to be more safe

i suggest corsair brand psu for nice pc power requirement
a hx 650 is good

If you want something solid and cheap, this is what I got :

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

No problems what so ever. Hefty OC on both my CPU and GTX670 without a hiccup.

but using Cooler Master eXtreme Power Plus 500W RS-500-PCAR-D3 still working with gtx 670 right?

Honestly, probably not. You are probably going to have to upgrade.

Newegg's power calculator says you'd be pulling 431 watts. According to the atx spec and this review:
http://www.hardwaresecrets.com/article/Cooler-Master-eX...
Your power supply is capable of delivering that level but with the ripple and noise levels you risk damaging your components, which you probably already are doing if you have a gts 250 in there...

Except that power supply is barely even made to handle 500W, not including efficiency.

Hardwaresecrets says it is capable of delivering very close to the specified wattage, I'm just worried that he's already damaged his components because of the nasty ripple and noise levels in the voltages at loads above 80%.

That is true, but I would feel better recommending something with a better rating. I did have a Extreme Power Plus and ran a 256-bit GTX460, which had 2 6-pins. That being said I did not run it for very long as I was waiting for my Antec NEO power supply to use.

You could use it, but at your own risk. I'm not saying it would blow up or something but still.

thanks guy. i will consider to replace new psu.

a hx 650 is best choice for it it have 52 a and modular which means power efficient