I just bought a new mobo XFX nForce 750a SLI. My pc specs are as below:

AMD Phenom 9550 X4 2.2GHz
Crucial 4GB RAM
Zotac 8800GT 512MB AMP! Edition + BFG 8800GT OCX 512MB
Cooler Master Real Power 620W

My problem is I can't run SLI on this mobo. The PC is perfectly fine and in fact I'm using it right now.

What I have done so far is:

1. Test the cards one by one using the primary PCIE slot (Both cards are fine)
2. Disabled On board graphics.
3. Disabled SLI Support (If enabled the PC won't boot up. The LCD goes black)
4. Setting and enabling SLI jumpers on the mobo to #pin 2-3 (#pin 1-3 is for normal state)

and what I haven't done is:

1. Clear CMOS
2. Updating the BIOS

Anyone have any idea? or someone who's using the same mobo could help. Please assist

Bro, before this i'm using ABIT KN9 SLI. I can run them without any problem. I don't know whether to update the bios since it only improve support for Phenom II series. Doesn't say anything about SLI.

hi there. 1st slot is the BFG. 2nd one Zotac.

Can I mix and match graphics cards?
In order to provide optimal symmetric scaling, SLI technology requires the NVIDIA GPUs to match. For example, a GeForce 7800 GTX must be paired with another GeForce 7800 GTX. Likewise, a GeForce 6600 GT must be paired with another GeForce 6600 GT. However, using the latest Release 80 or later graphics drivers, NVIDIA GPUs sold by different manufacturers can be used together in an SLI configuration. For example, a GeForce 7800 GT from vendor ABC can be matched with a GeForce 7800 GT from vendor XYZ.

Can I mix and match graphics cards is one of them is overclocked by the manufacturer?
Yes. A GeForce 7800 GTX that is overclocked (for example BFG GeForce 7800 GTX OC) can be mixed with a standard clocked GeForce 7800 GTX.

Those are taken from the Nvidia website. Source

whoa.. u flashed ur card? I don't know if I can do that

BFG has more speed than the Zotac. I've tried that too bro. I switched those cards around just now.. tak jadi apa² pun. But I'll give it another shot

This post has been edited by Eyern: Feb 8 2009, 11:19 PM

Hi there Najmods, sorry to ask but how do I set up the jumper to 8X? Your saying that you want me change those jumpers to normal state?

I did that in BIOS cos there is no SLI configuration in the NVIDIA CP.

You have to register to download the manuals . Yea.. I know the green is the main one and the four jumpers were all in SLI mode when I bought the mobo (from the top, two rows covered, one row empty, two rows covered and one empty row at the bottom). I've gone throughout the manual but I couldn't find how to change the speeds to X8. But there's a short topic explaining about PCI and PCIE slots.

2.5.3 PCI and PCI Express slots
Install PCI Express X1 graphics card into slot “PCIE2” or "PCIE3".
Install PCI Express X4 graphics card into slot “PCIE1”.
Install PCI Express X4 graphics card into slot “PCIE4”.
Install PCI card into slots “PCI1” or “PCI2” or "PCI3".

I disabled the SLI support in the BIOS because if I enabled it my computer won't boot up. The LCD screen goes black. Yes, I've set the correct SLI jumpers and I even remove the jumpers and put it all back again in SLI mode.. still cannot run SLI.

Of course I use the SLI bridge lol. Yeah, kinda weird. If I enabled SLI support in the BIOS and mobo, the computer won't go to windows. I think it's other one u need to enabled.

What ASUS mobo are u using? I have no idea how to enable the SLI. I've emailed XFX, they told me to use identical cards lol.

Btw, sorry for the late reply =p.

Bersabar bro. Untill today, I still can't figure out where lies the problem. I've emailed XFX support. They told me to use identical cards. Wtf?

Khabar baik and hi to u too. PM liangtucky cos u guys have the same problem. Mine is a different one.

Btw, my problem solved. Want to know why? I threw the board away and bought an Asus (2nd hand ). Works like a charm. Currently running SLI without any problem haha.