Sli gtx580 lightning extreme problem

[Harry604]

so im running 2 gtx580 lightning extreme cards

playing bf3 my fps dip into the 30s and the cards are only running at 50-70 percent
i was getting better fps running one card and it was runnign at 99 precent

cpu percentage in games goes from 70-90

my cpu is a 1100t at 4.0ghz 16gb ram vengence

my psu is ax750 watt 80 plus gold corsair

is my cpu bottlenecking or my psu ?

what cpu should i get if its the problem or new psu??

 

[beltzy]

Couldn't find the min specs for SLI, but for a single Lightning Extreme

244W Maximum Graphics Card Power (W)
600W Minimum System Power Requirement (W)

Could be your PSU. 600+244= bad overly simplistic analysis

 

[ko888]

For a system running with two reference clocked GeForce GTX 580 graphics cards in 2-way SLI mode NVIDIA specifies a minimum 900 Watt or greater power supply with a combined +12 Volt continuous current rating of 62 Amps or greater and with at least two 6-pin and two 8-pin PCI-Express Supplementary Power Connectors.

It's not the power supply's wattage recommendation that needs to be met, in fact it can be ignored. The critical specification that must be met is the combined +12 Volt continuous current rating requirement. If this specification can't be met by the power supply your system isn't going to be properly powered. Those that just focus on power supply wattage don't know how to properly size a PSU.

Your Corsair Professional Series Gold AX750 (CMPSU-750AX), with its +12 Volt continuous current rating of 62 Amps and four 6+2-pin PCI-Express Supplementary Power Connectors, just meets the minimum requirements.

If the graphics cards have been overclocked (i.e. factory or user) in any way they will be consuming more power.

Make sure you are using the latest NVIDIA GeForce 285.62 Driver that has the SLI profile for Battlefield 3 and that SLI is enabled in the NVIDIA Control Panel.

 

[Helltech]

I'm going to guess its the PSU. When Guru 3D did a benchmark of stock 580 SLI they were pulling 719w. You have overclocked cards. So you are probably pushing that Corsair (even though its an amazing PSU) to its absolute max. Which even if it wasn't your PSU causing problems, isn't a safe thing to do.

That and your 1100T probably needs to overclocked a bit to keep up with those massive cards. Then you overclock the CPU and add more power consumption..... and yeah.

 

[Warmacblu]

You power supply is definitely the issue here. A single GTX 580 requires a recommended minimum of 600 - 650 watts. For two GTX 580's I would run nothing less than a 1000 watt power supply.

 

[Harry604]

so a psu cant hold back a video card and make fps drop a lot

 

[Helltech]

If it does not supply the card with sufficient power I suppose anything is possible. As I said even if it wasn't the PSU that is causing this issue you still need a PSU upgrade regardless.