Will my Psu Be able to run two 4890's in Crossfire ?

drkzin

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Your power supply unit, OCZ StealthXStream 700W PSU has an overall of 72 amps on the +12V railings (18A on each of the four +12V railings). It has way enough amps for 2-way CrossfireX but the PSU is lacking the 6-pin pci-e power connectors. For one HD 4890, you would need 2x6-pin pci-e power connectors yet your PSU has one 6-pin and one 6+2 pin. That would mean, if you want to keep the power supply unit (which i recommend doing), then you should buy a molex to 6-pin pci-e connector adapter. This just basically transforms 2x molex connectors into one 6-pin connector, although you would need 2 of those adapters in order to have enough pins for your second HD 4890.

Sources:
Your card on newegg (ATI website made me rage, loaded too slow):http://www.newegg.com/Product/Product.aspx?Item=N82E16814150438&cm_re=HD_4890-_-14-150-438-_-Product

Your power supply on newegg:http://www.newegg.com/product/product.aspx?Item=N82E16817341019

Just reply if you need anything else
 

72x12=864watts!!!!! It is not calculated that way! That power supply has 675 watts for all the +volt rails if we use it all as +12 volts we get 675/12=56.25 amps and that is not leaving any power for the +3.3 and +5 volts.
That does not change it, it is still big enough for the Crossfire system.
 

gidgiddonihah

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Ok go to this site and plug in your info: It will calculate all of your wattage for you ;a). It has been very benificail and trust me: Its Acrurate... lol

http://www.thermaltake.outervision.com/
 

vvhocare5

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Two thoughts?

If you are buying 2 video cards - go buy a good PSU, and if you do not know what you are doing, make sure it says crossfire or SLI ready. The number of questions from people buying highend graphics cards and then asking about their PSU is amazing. I say try it and if it doesnt work, go buy a new power supply.

Second, why buy ATI 48xx anything now as capt points out. That one 5780 card will be faster (look at the benchmarks) and the same cost - with less power. If you cannot figure out you PSU, thats the answer....

Good luck
 

noob2222

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:lol: :lol: :lol: :lol:
try to use this with any decent high end video card and your screwed. This statement couldn't be more false.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817165004
46A to the 5v .... :non:
:pt1cable: :pt1cable: :pt1cable:

I prefer overkill, most psu run more efficient when they are at lighter loads, and less efficient at full load, plus upgrading in the future won't have to inlclude your psu.
 

gidgiddonihah

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gidgiddonihah

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Im thinking... Im thinking... Im thinking... (Sorry lol)

NO!!! Well it... With the GTX 285 SLI'ed then ya it will be cutting very close but look at the PSU calc site that i mentioned up further...

And try to go 1000watts it will work and leave you with a little breathing room to say the least hehe...
 

Dougx1317

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I was also considering getting a second 4890 for crossfire. I have a 700W FSP power supply. It says that it has 18 amps on each of the 4 +12v rails. How can that add up to 700W? 700w/12v=58amps Is this a typo on their part or am I calculating it wrong?
 
You should open a new thread as well. The 18 amp on each rail is the max for individual rail, it does not mean that you add them all up together because they would not all be at max at any given time. Most good quality state the max wattage for each voltage under their amp rating and that is the number that you divide with the volts to get the max amps.