8800 GTS SLi won't enable

[sectrix]

Ok, got two video cards, SLi won't enable. Here's the specs:

MoBo:
- ASUS M2N32-SLi Deluxe

GPUs:
- MSI 8800 GTS 640MB
- XFX 8800 GTS 320MB

I have BIOS, drivers updated. Both cards are recognized by Device Manager. NVidia's CP doesn't have the SLi enable option in the 3D settings screen, no congratulations message when I boot up. No jumpers or little cards to flip around, nothing in BIOS to enable both PCI-E slots, bridge installed, both cards work on either slot.

Possibly because I have two different card mfgrs with two different memory capacities? GPUs are the same though. Really don't wanna wipe everything to get this to work. Any knowledge is appreciated.

 

[Lmeow]

Place the 8800 GTS 320MB in your primary SLI slot, and the 8800 GTS 640MB in the secondary slot.

Remove all drivers, reinstall them, open regedit and go to HLKM/SOFTWARE/NVIDIA Corporation/
Global/NVTweak/ and add a DWORD(32-bit) Value called "Coolbits" with hex value "18". Reboot.

Hope that works.

 

[Mousemonkey]

I'm not sure that those two cards can be Sli'd, but I stand to be corrected.

 

[FunSurfer]

You know that even if you do manage to SLI the two cards, games will 'see' only 320MB VRAM, so you will get in many cases better performance from a single 8800GTS640...

 

[4745454b]

They should SLI. I don't think the single 640 card would be faster. Make sure each card is good by using it all by itself, and do make sure the 320 is in the primary/master slot. You might also want to double check the SLI bridge and make sure its on tight.

 

[ubernoobie]

you actually dont need the sli bridge to sli lol. But put it on, It will increase performance by a lot (10%+) and every bit counts.(with good cards) and are you sure both cards have enough power? Maybe you have 1 card with power and other without power or something lol

 

[sectrix]

Thanks for the CoolBits tip. I suppose it would help if I read NVidia's directions.

The SLi worked as advertised; I didn't even reinstall the drivers.

I downloaded two freeish benchmarking programs to see if there was any difference.
And boy was there!

8800GTS 640MB:
FurMark: 1746
PerformanceTest: 991 (1402/408/55)

8800GTS 320MB SLI:
FurMark: 1734
PerformanceTest: 974.5(1425/408/47)

So let that be a lesson to those who don't know: there is no point in sacrificing memory for SLI capability.

 

[Mousemonkey]

Thanks for the CoolBits tip. I suppose it would help if I read NVidia's directions.

The SLi worked as advertised; I didn't even reinstall the drivers.

I downloaded two freeish benchmarking programs to see if there was any difference.
And boy was there!

8800GTS 640MB:
FurMark: 1746
PerformanceTest: 991 (1402/408/55)

8800GTS 320MB SLI:
FurMark: 1734
PerformanceTest: 974.5(1425/408/47)

So let that be a lesson to those who don't know: there is no point in sacrificing memory for SLI capability.

Well done, you are one up on me then because I had issues a couple of years ago trying to get a 640 and 320mb card to SLi and they just didn't want to work for me.

 

[4745454b]

Those scores make no sense. The 320MB SLI should be higher then the single 640 card. They have the same specs, just less memory. Shouldn't matter at 1680:1050.

 

[Lmeow]

Thanks for the CoolBits tip. I suppose it would help if I read NVidia's directions.

The SLi worked as advertised; I didn't even reinstall the drivers.

I downloaded two freeish benchmarking programs to see if there was any difference.
And boy was there!

8800GTS 640MB:
FurMark: 1746
PerformanceTest: 991 (1402/408/55)

8800GTS 320MB SLI:
FurMark: 1734
PerformanceTest: 974.5(1425/408/47)

So let that be a lesson to those who don't know: there is no point in sacrificing memory for SLI capability.

Good to know that it works, especially without having to remove the drivers, although bad to know that it doesn't seem to give much performance benefit. Try using lower resolutions in games and see if you can see any performance benefit.