hi, i am new in this area, but i have one question on gtx980 power supply. everyone said minimum 500w, however, i confuse.
i have i7 4770
psu 460W
ram 8G, and want to upgrade to gtx980. i calculate that the cpu take 84 w, gpu take 165w, and motherboard and ram, hard drive and other(like keyboard)take about 50w, so they should be:84+165+50=299w. i do not over clock or other. just sometime playing games. why everone said at least 500w? the 84 w and 165w are found in their website, like intel and nvidia website.

 

460w is an odd number for a mainstream PSU. Do you have a model number for that power supply?
 
They say 500w as an overall recommendation, considering all power supplies on the market. If you have a poorly built PSU that might not be bronze certified or higher, you will definitely need a 500w PSU because older/poorly built PSU's are not really built to take much more than a 50% load for everyday gaming.
 
If you have a high end PSU that is gold or platinum certified... You would definitely be able to support that videocard.

You need to have 20A on the 12V+ rail which you don't find on a 430W PSU. But basically, a 430W PSU is designed to power the basics and an expansion card, but not a 160W GPU with 2 PCI-e connectors, which you may not even have two of those. The PSU has diffrient voltages and each voltage have a maximum ampridge on each voltage, for the case of the 980, it would be required to have about 18A and ideal to have 20A.

actually, i have dell xps 8700, and don't have much budget to build a new one.  The dell PSU 460w. 

GYD101
actually, i have dell xps 8700, and don't have much budget to build a new one.  The dell PSU 460w. 

Oh Now you Tell Us

That PSU is kind of scary. You should be able to watch Newegg.com for a week and they will put a 500-650W PSU up for sale at $40-$70. Or you could probably buy a nice 500W PSU for $60-$80. Just make sure it has 20A on its 12V+ rail and two PCI-e cables, preferably both being 6+2 cables. Otherwise a 6 pin cable and a 6+2 would work (one of each). Also, try to buy a bronze rated at least as its going to save some cash on electricity and it shows better quality.

EDIT: Just noticed a corsair CX 750 is on sale today for $80 and a $10 rebate, so it's really $70. It's really nice and you can pick it up on Newegg, but it's the mobile store so you need to use your phone. Generally though, there's one on sale nearly everyday if you wait.