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View Full Version : How Many Amps on the 12v rail for GTX 280 SLI


john19055
08-27-08, 04:29 AM
I keep hearing I will need a 1000watt power supply ,but most reviews I see say the max with a load is 564watts and that is includeing the motherboard and CPU and the harddrives and the other stuff.I read one review saying it will need around 55amps on the 12v rail for SLI .What would be the smallest Power supply for a GTX 280 in SLI.Should a
800watt SilverStone OP with 66amps on the 12v rail be enough,or would a PC Power + Cooling 750watt with 60amp on the 12v rail be enough.Because I don't think my OP SilverStone 650watt is going to be enough with it's 54amps if I go with SLI.

john19055
08-27-08, 05:28 PM
Do you think 66amps on the 12v rail will be enough for two GTX 280 if I decide to go with SLI.

Eliminator
08-27-08, 06:40 PM
i think thats enough

gstanford
08-28-08, 04:32 AM
Why guess?

go here: http://www.slizone.com/object/slizone_build_psu.html

You will see a list of SLI certified PSU's for various SLI configurations.

Having an adequate PSU in your system is critical for system stability and its not something I'd blindly guess about.

john19055
08-28-08, 06:45 AM
Because all of them list a 1000 watt,1200watts and 1500watts ,and I do not think I need one that large ,All the reviews I have seen say that the max load of a whole system with two GTX 280's running in SLI draw around 534 watts to 564 watts and that is with a overclocked CPU in some plus the motherboard and hardrives and Fans and HD-DVD burners and the rest of the stuff.Even if you pushed it to 600watts ,that still would just be 50amps on the 12v rail.And other reviews I have seen said you need at least 55amps in a SLI system fully loaded.Since all 1000watts power supply are not made the same I have seen some that say the maxium on the 12v raills is 68.5 and some 70amps all the way up to 82amps.I have seen plenty of them running off of a Rosewill RX950-D-B 950W and it only has 67.5 amps on the 12v rail.I just don't have $250 to spend on a power supply even tho I know it one of the most important parts.I just looking for one that will do the job. I always had great luck with SilverStone.

gstanford
08-28-08, 07:23 AM
Well, if you think you know better than nvidia go right ahead... but you may want to think twice about coming out with a sob story/GTX280 sucks story if your system doesn't work properly.

Eliminator
08-28-08, 03:44 PM
Well, if you think you know better than nvidia go right ahead... but you may want to think twice about coming out with a sob story/GTX280 sucks story if your system doesn't work properly.
no he has a valid point... nvidia just lists the top of the line models... you dont need a 1kw supply for 2x GTX 280... probably a 700W with 50A+ on the 12V will suffice

cocokiwi
08-28-08, 06:36 PM
:DDo you think 66amps on the 12v rail will be enough for two GTX 280 if I decide to go with SLI.



I have a GTX-280 and it,s running very happy on a 850 watt Antec.

I had a 700w and had had it around a mth wneh I got this Video card!

Called EVGA and they told me it was Fine,RIIIGHT! BEEEP.Bip.bip.Bip went my MB and the led went Green then RED...power supply!sheee! so I took back the one I had and got a 850w Antec...open box..got it for SAME price as old one!(grin)

Rule of thumb! 1 > make sure the supply has 2 x 8pin plug for VIDEO device,and the 6pin!NOT the one that comes out of the power supply case,assuming you have plug setup..
with those you have THREE coming from the case..MAIN power MB plug/4 pin 12 v power/and the 8 pin 12 v power..the difference is the Plug is different and the wires goto all the connectors as in Yellow and the black.the yellow one don't goto the last pair on the end with the 800 watt,with the 700w all of the top yellow wires go to every pin on top as do the black ones on the bottom,there is a difference.so don't go forcing the thing into the board socket..it will fit with a little push! BUT! IT DON'T GO THERE!when you get the power supply,look at the end of the two cables and you will see what I,m talking about!

2 > make sure it has 800 watts or above! EVGA ask for the TOTAL of
ALL FOUR 6pin plugins..the problem is you only use 3 of them with
the Patch plugs that come with it! a 700w would only have:

18 amps each 18 x 3 = 48amps Not 56 amps The card has a controller for the power that can idle at 24 watts and ripp along at 250 wats Max..double this if you have more cards!
a 1000 watt for a 3 SLI system:D:captnkill:


Good Luck!

Dennis

Absolution
08-30-08, 03:05 AM
Fixed it for ya(capital letters)...

OP: go find some reviews of SLI 280's and see what PSU's they used...which you have apparently already done.

What I have seen is always in the 750-1000w range though, so I'm sure a GOOD 750w would work fine assuming it is a quality PSU.

I would be surprised if even a 650watt psu didn't work for 2 280's. Most people completely over estimate their power usage.

vgame64
09-17-08, 10:11 AM
Q6600 @ 3.0GHz, 8 GB of DDR2, eVGA 780i motherboard, 2 10k 80 GB Raptors, 320 GB 7200 + 750 GB 7200 SATA drives, 2 optical drives, and 2xGTX280's @ 681MHz Core/1253MHz Memory/1466MHz Shader.

All on a Coolermaster Real Power Pro 750W with no problems. (It has 76 Amps across 4 12V lines)

So you should be fine!

Quick420
09-17-08, 10:28 AM
Do you think 66amps on the 12v rail will be enough for two GTX 280 if I decide to go with SLI.

You are good to go m8:p I've been noticing a HUGE improvement in the quality of Psu's in the last 2 years,as more and more people shy away from the Oem(Dell etc)market.(nana2)