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PSU for 295x2 in crossfire.

Jacky60

Jacky60

Jacky60

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Picking up 2 of the 295x2s and wondering about new PSU, currently got EVGA G2 1300W and some reviews say you need over 1300W whereas Toms recent article says you can go xfire with just 1000W.
http://www.tomshardware.com/reviews/amd-r9-295x2-1000w-psu,3907.html

Which is correct? the EVGA 1300W G2 is on list of approved AMD PSUs but I suspect it won't but it. Any opinions?
I have a 4770k at 4.7, a single SSD and a few fans but its a lean system.
 
I wouldn't be considering lower than 1300w PSU for two or them beasts.

I'm guessing they were talking about some crazy well built 1000w platinum rated superflower unit, because I'm 90% sure that it will be operating over its rated specs at points.


Gibbo posted yesterday concerning this and he knows more than me so here is the copy paste:


Gibbo said:
The 1000W will do it, but you will be exceeding the PSU's specification and as such I would say ticking time bomb long term.

1300W ideally and for two of them I'd simply just get the Corsair 1500W or EVGA 1600W. :)
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Well I have the EVGA 1300W G2 and it's nearly platinum level performance and
I'm only rocking 4 overclocked cores not 6 like most review sites so I will give it a go. Next step 4k Woohoo!
 
Thanks, I'm going to put the 1300W through it's paces, I still can't understand how some sites report 1350W at the wall when others say 1000W is OK. Even platinum 1000W seems inadequate to me but once more into the breach!
 
Remember that PSUs are rated for what they can provide to the PC, rather than what they draw from the wall (except for no-name PSUs, they tend to be rated by a random number the salesman thought of!). This means a 1000W PSU producing 1000W to the PC at 85% efficiency (for example) will be pulling 1176W from the wall.
 
Confused Stu said:
Remember that PSUs are rated for what they can provide to the PC, rather than what they draw from the wall (except for no-name PSUs, they tend to be rated by a random number the salesman thought of!). This means a 1000W PSU producing 1000W to the PC at 85% efficiency (for example) will be pulling 1176W from the wall.
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Hey Thanks for that I never knew it so I didn't remember:). I did the calculator thing
http://www.extreme.outervision.com/index.jsp and came out at 1284W usage and a recommended 1334W PSU which is as annoyingly marginal as these things get! Neither here not there but ever so slightly over what I have. First rule of Power supplies is 'Always buy the very biggest there is' regardless.
 
I have 3x290's at 1000Mhz gpu and my PSU has no probs. I bought mine specifically to have some ltd headroom with current setup. EVGA PSU are 10 year guarantee I'd get the EVGA 1600W G2 if I were you. Then hopefully you never need to buy another. I say that cos I have Enermasx 1250 and EVGA 1300 and thought I had all I ever needed but 1500W/1600W were much more expensive then (Last Nov).
 
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Don't skimp on the PSU for these cards, if I was building a rig with two of these cards I would use a good quality PSU for each 295X2.
 
VincentHanna said:
What about a PSU for a 295x2 + 290x in Tri-fire?
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Your still going to need 1200 watts for comfort, Seasonic is your best bet. Easist way to work out yiur neees is 300 watts per GPU plus 300 for everything else. Your not good not going to be able max all that out unless you run 3D mark and prime95 at the same time in gaming it should be bit less.
 
Kaapstad said:
Don't skimp on the PSU for these cards, if I was building a rig with two of these cards I would use a good quality PSU for each 295X2.
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Well I could easily put together my Enermax 1250 and the G2 1300 then buy cheapo 1300 for domestic use. Not sure how to rock 2 PSUs in one case i.e.how to short PSU to fire up not on mobo. But that makes sense.
 
Jacky60 said:
Picking up 2 of the 295x2s and wondering about new PSU, currently got EVGA G2 1300W and some reviews say you need over 1300W whereas Toms recent article says you can go xfire with just 1000W.
http://www.tomshardware.com/reviews/amd-r9-295x2-1000w-psu,3907.html

Which is correct? the EVGA 1300W G2 is on list of approved AMD PSUs but I suspect it won't but it. Any opinions?
I have a 4770k at 4.7, a single SSD and a few fans but its a lean system.
Click to expand...

if you didnt get the last top haswel-E processor, i wouldn't bother crossfire, the previous 1000$ cpu from intel bottleneck the crossfire.
1 290 + 295X2 should be enough.
draw from the wall is between 900 and 1100watt depanding on how efficient your PSU is, need 100A combined, and 30A per connector
 
AlamoX said:
if you didnt get the last top haswel-E processor, i wouldn't bother crossfire, the previous 1000$ cpu from intel bottleneck the crossfire.
1 290 + 295X2 should be enough.
draw from the wall is between 900 and 1100watt depanding on how efficient your PSU is, need 100A combined, and 30A per connector
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A 4930k will run two x 295X2s in CF with ease.

As long as you are using a Hex core bottlenecking is down to the resolution used not the CPU.
 
Kaapstad said:
A 4930k will run two x 295X2s in CF with ease.

As long as you are using a Hex core bottlenecking is down to the resolution used not the CPU.
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i saw reviews of them running on firestrike and 3Dmark, the results show the score cpu bound, forgot what cpu it was i think 3960X, look at minute 10:00

 
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AlamoX said:
i saw reviews of them running on firestrike and 3Dmark, the results show the score cpu bound, forgot what cpu it was i think 3960X, look at minute 10:00

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At minute 10:00 that is the Vantage bench, it is totally obsolete and DX10 as well.

If you are going to use Futuremark benches to check CPU performance and GPU scaling you need to use the Extreme Versions as these use realistic resolutions and workloads that more closely resemble what you get in games.

A very good bench for doing the above is Firestrike Extreme which runs @1440p and shows GPU scaling from 1 to 4 cards used very well.

If you look around the bench threads on these forums you will see plenty of posts of mine run at 1600p or 4K where 4 Hawaii GPUs have scaled very well indeed. The other thing about my Hawaii GPUs is they are single cards watercooled meaning they are significantly faster than a pair of 295X2s, or putting it another way if my cards can scale ok then a pair of 295X2s should have no problem doing the same.
 
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