I have a Gigabyte motherboard GA-M750SLI-DS4
It has the F7 bios (had F8 but will explain later as to why a downgrade)
6 gigs ram at 1066 using all 4 Slots
Raid 2x 640 gig western digitals
Both PCIE x16/x8 slots used in 8800gt zotac amp+ in SLI setup
AMD 940 3.0 x4 AM2+
600 watt psu
Vista Home Premium x64
PSU details "SeaSonic S12-600 600W ATX12V / EPS12V SLI Certified CrossFire Ready Active PFC Power Supply"
Output +3.3V@30A, +5V@30A, +12V1@18A, +12V2@18A, -12V@0.8A, +5VSB@2A
Power efficiency Up to 85%
I recently purchased an Auzentech Forte PCIE x1 audio card (super awesome)
As you can see the pciex1's are inbetween the X16/x8 slots. (both run at x8 when sli is being used)
When I install the audio card in to one or the other PCIEx1 slot the PCIE x16 or x8 slot encounters a conflict. If its placed in the pciex1 right below the top pcie x16 slot, (once in windows not during boot up or startup into windows) it will start to flicker then all of a sudden all video disapears and I get that generic error on the screen saying that it is unplugged.
If its placed right above the PCIE x8 I will get an error in windows under the Device Manager saying this has failed to start and there are no more addresses available ??? One time it even said that box that the bios may need to be updated. Well it was already updated so that the AMD 940 would work on this motherboard, however a slightly older bios f7 was also available that supported this processor so I reflashed to this older version to see if it would help. It did not. Either way, SLI worked but audio card didn't.
Now if I remove the video card from the x8 slot and place the audio card right above it in the pciex1 slot. The audio card will work and I will have video from the x16 (which is how its running right now).
Ive uninstalled Nvidia drivers and reinstalled in many different sequences with the audio card drivers but no go. I even went into the bios and disabled everything I dont use... ie fire-wire, parallel, ect.. hopeing maybe it would free up an address ??? just grasping at straws you might say.
I'm almost ready to format it and give that a try however I would prefer not to go threw the whole backing up and restoring then finding it was a waste of time and effort.
I want to have my 8800gt cards back in SLI and have that audio card running, I really dont want to dish out 300+ on a single video card just yet since these puppies work just fine for my gaming needs.
So what do you guys think maybe the issue is, btw gigabyte rep seems to believe that it should work : SLI with audio card in pcie x1, hes asked me to purchase another pciex1 card and see if its the same issue. Which I have, but has not come by UPS just yet.
Complex and interesting issue - I'll let this one 'percolate' in my subconscious for a bit. You are tackling it correctly - often, I answer questions from people about PCIe capabilities and the effects of 'who's plugged in where' - and, always I start from their system block diagram... And yours does look like this should not be a problem... One thing I'd ask as a preliminary - do you have the 'booster' X4 PCIe supply plug connected - I ask as someone just recently PM'd me regarding a really peculiar problem, on a similar (but not the same exact model) MOBO that was solved by adding this PSU connector!
Right before I hit the sack I pulled all the case fans. I checked the power connectors on the mobo, they looked good and tight but looks are deceiving (from past experience) so I reset them. I placed my 2nd video card in and crossed my fingers and said a little prayer when I hit the power button.
Long behold it works, SLI and the audio card. So it is a power issue. I will tinker with the fans and get them on molox connectors later. If that doesn't work, I see a new power supply in the future.