Another "what size PS" thread

[boeckelr]

Hi guys,

I am building a 2500k system...with a Gigabyte Z68 motherboard, an ATI HD6870 video card, 8GB ram.

I am stuck on what size power supply to buy. I want to buy for the future - in case I decide to overclock my 2500k. Also, in the future I may want to either add a second HD6870 video card, or even replace it with something more powerful.

I know that I should stick with the Antecs, Corsairs, Coolermasters, OCZ,s, SeaSonics etc....but what size should I get? I know that right now a 650watt would probably be sufficient...but I dont want to have to go out and buy another PS in a year or two when I start overclocking or doing crossfire.

Also - I have seen brands that I wouldnt normally associate with high end power supplies are made by SeaSonic - i.e. some XFC's....are they all right to buy?

So would a 750watt PS from one of those company's I named be enough? Or should I go for an 800 or 850? Sorry if these are stupid questions. I have asked this on other forums and have received a variety of different opinions.

Thanks,
Mike

 

[ctk1981]

650W would cover the system now and even overclocking the 2500K. If you plan to add another card for crossfire, then I'd go 850. The new 7970 draws less power than previous generation at idle, more at load but still less than most nvidia parts, so if you stick with a single card for a future upgrade chances are the 650 would still be good.

Basically I'd decide now, if you plan on crossfire somewhere down the road go larger. If you're going to stick with a single card solution 650 would cover it. I'm extremely pleased with my Seasonic X 650 Gold.

 

[lehtv]

6870 needs two PCIe connectors and 430W and lower units only have one. Since 6870 doesn't use more than about 140W, a 500W unit is more than sufficiently powerful.

If you want to be covered for upgrades to a more power hungry GPU or 6870 crossfire, then get 650W+ unit. XFX 650W is $60 AR on newegg and $50 AR on us.ncix.com (if you're in the US) and $45 AR on ncix.ca (if you're in Canada).

FYI, many 650W units only have two PCIe connectors so they're not crossfire compatible out of the box, while 750W+ units (invariably) have 4 PCIe connecotrs. But in any case a good dual or single rail 650W unit will power 6870 crossfire with molex->PCIe adapters without an issue. The XFX has 4 PCIe connectors, thankfully.

650W would cover the system now and even overclocking the 2500K. If you plan to add another card for crossfire, then I'd go 850.

A good 500W unit has enough room for overclocking the 2500K. 850W is overkill for 6870 crossfire, combined they only draw less than 300W, so a 650W unit will handle that along with OC 2500K without any issue.