4870X2 on OCZ GameXStream 850W?

[lehtv]

Hey

Does the OCZ GameXStream 850W provide enough amps for 4870X2? It has the following specs:

I've read opinions of both sides, e.g. "yes", "yes, no problem unless you overclock" and "completely inadequate". But I've found none that was convincingly justified, perhaps partly because of my noob understanding of the issue at hand.

I read here that 4870X2 requires about 20-25 amps and wouldn't work on GameXStream 850W because each 12V rail provides only 18A (20A according to the pic above). But isn't two 12v rails used for the graphics card (one 6pin and one 8pin connector), totalling 40 amps max?

Someone help please. Also how do I judge how many amps a graphics card requires? The ATI website doesn't seem to provide that info.

ADDED: As to the last question - is it just that I divide the watt requirement by the voltage used? If 4870x2 requires two PCI-e connectors and they're in different 12V rails, I should divide 270W (read that's 4870X2 under full load) by 24 to get amps per rail, right?

 

[|LBTG|Theos]

I am not entirely sure about this but I think you are looking for the combined amps over the 2 12v rails, I am sure someone else will be able to tell you exactly

In terms of the PSU being sufficient I would have to say it would be fine. I am currently running 4870x2 and have been for over a year with a Hiper 880w psu which only has 18A on the 12v rails and it has never skipped a beat. Granted I have never overclocked the gfx card (not that it really needs to be, nor would you see a massive improvement without melting it on stock cooling) However it is Handling a 1Ghz cpu overclock very well.

Hope this Helps

 

[rene.agac]

I have 4870x2 and OCZ GameXStreme 850W and it works just fine. GPU not oc/ed (no need & there isn't much of a headroom anyway unless you want the fan to be on 50%+).
Running C2D E8500@4GHz

 

[jorzeh]

im using a 4870x2 on a 700w ocz with no problem and my cpu is at 3.8Ghz no problems here.

 

[littlepuppy]

Im using a GTX295 on a bequiet 450w, max draw from the wall I have seen is 360w, so PSU is only 60 - 70% utilised....

These wattage figures are so overblown its a joke...

 

[lehtv]

thanks, that helps

 

[Lightnix]

I don't see why its potentially needing 25 amps would be a problem. The card won't draw all of its power from one 12v rail, that'd be stupid. It'll at the very least be pulling the 150W/75W (depending on PCI-E specification - that's 12.5A or 6.25A on the 12v line) from the motherboard from a different rail to the PCI-E power cables.