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

i thinks you must updated bios first bro...make it compitable for sli...btw ur gc also no same brand..maybe it cannot make sli..what do you think..

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.

which 1 card you put at 1st slot?

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

For SLI to work, ideally you should use two identical cards.

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

i'm also using 7900gto flashed to gtx bios..can work sli'ed with XFX 7900gtx..no problem...

btw..which card more higher mem/core..slot it to 1st slot...it's work for me...

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

i'm just bought from other forumer also..already flashed it....hehehehehe..but it's working for me....

I heard lots of bad reviews regarding this particular mobo, but anyhow I'll try to help you out of it.

First try to set up the jumper to X8 on both slots, and run with single card first, boot windows and confirm whether it runs at X8 speed. If it does, try to enable SLi in BIOS while still running with single card. If it does boot, install 2nd card on the next boot and see whether it will be fine afterwards

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?

You did that via BIOS or NVIDIA CP?

Read the manual (I can't download it, XFX site don't have any link) how to configure both high speed PCIe to work at X8 speeds, remember the primary slot is the GREEN one not the upper black one. From this picture here you can see all the jumper are facing down, if I'm not wrong if you want to enable SLi set all the 4 row to face up

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".

Did you enable it in the BIOS and did you set the appropriate jumpers on your mobo? Sounds weird but have you set up the jumpers correctly? Look at it again carefully which pin is which pin...

The SLI Jumpers... and you did use a SLI bridge right? Kinda weird too that you disable the SLI in your BIOS but you enable it on your mobo?

This post has been edited by ndgoh: Feb 15 2009, 01:51 AM

XFX 750a SLi having problem with 8800GT before it supporting hybird SLi. Once i hv that mobo before. I just can't make it work. Damn dulan, I change to Asus. Now right fine.

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.

LOl....same problem here bro....best part is...i cant even use a dam 9600GT on that board....if i put a card on that board...and link it with the monitor....the monitor will have totally no signal and the board bios just shows 88 for the next24 hour..

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?