PSU question: Is 850W enough for 3 cards??

[DiamondHunter]

Properly undervolted 7950 (I run mine at 1.075v that gives me 630kH) draws just under 200Wa. Your system is using between 100-160wa.

In one of my systems I run 3x5850 and at the wall I have 500 wa consumption.

You should be able to run comfortably 3x 7950/7970 or 4 older cards at efficient PSU utilization.

Kill-A-Watt is awesome tool when optimizing your miner settings. Remember, you want to undervolt and overclock your GPUs.

 

[zackclark70]

i run 3 cards on a 750w psu ( 700-725w  at the wall )

That's easy...some cards only pull 15watts!

The poster I was referring to was running 3 7950s (underclocked).

If he was running these under load (scrypt mining/over clocked) he would not be able to run them with a 850psu.  Additionally he would be burning a lot of wasted power because of the efficiency drop.

sorry i ment to say i have 3 7950s runing at 630kh each

edit 1050 core 1250 ram 1.050v core 55% fan

Oh, ok.  That's quite good.

But you still would be at (or near %) capacity of psu which kills your power efficiency.  You must also be running other low draw hardware (like ssd/lower mem/ semperon/Ect).  Like I said it depends on a ton of factors.  And every online calculator I have seen would recommend a larger psu for those 3 cards.


Edit...re-read your post...you are at about 97% of capacity.

that rig is a 1090t cpu 256gb ssd cpu watercooling ( 25w waterpump ) 6 120mm fans  8gb ddr3 1600and a led  monator lol have a look at it its my card testing rig / gaming rig lol
http://s1315.photobucket.com/user/zackclark70/library/#/user/zackclark70/library/

edit its a hx750 psu so max it can pull from the wall 850w ( at 90% efficiency )

edit croshair iv motherboard

[Singlebyte]

You have basically what I have for my main machine.  I have a 1055t overclocked ( no water cooling....lol) with ssd as boot drive, and 8gb. My main minning rig is using semperon on a ASROCK|970 EXTREME4 AM3+ 970 R. And a 1000 gold 80 plus power supply.

[zackclark70]

im using reaper so mem clocks dont make much difrents  1250 is the standard seting on my cards
it makes 4w difrents lowering the mem to 1000 on the 7950 vaporx oc edition but makes them less stable and gets 10kh less

( i have 20 rigs with 4 cards and 1 test rig with 3 cards )

picks of my test rig its only cpu watercooled because i game on that rig ( amd 1090t ) http://s1315.photobucket.com/user/zackclark70/library/

Thanks for the pictures. Nice rig, I like your fan setup.
My 3x 7950 system is a milk crate setup with a single 20 inch box fan blowing across it. The box fan uses 80 Watts even on the lowest setting. I'm thinking of moving to a 3x 120mm fan setup like yours to save some Watts.

That radiator for your CPU is insane! Its like something off a motorcycle or small car! I like it.

Now, if only I could work my way up to 20 rigs like you.

that rad is good for 1.2kw at 10c delta with 9 low speed 120mm fans the rad is a mo-ra 1080 i think

milk crate rigs get to hot because of room temp ( my rigs are staked to draw air from the house and blow hot air out the windows lol )

i think the 120mm fans are 1.2w each lol

if you need more info or have questions pm me

zack