[1 BTC BOUNTY] More than 2 card issue - M4A79XTD Evo

[Yanz]

I have the Asus M4A79XTD Evo (2 x16 and 2 x1 slots) and I can't get it to run more than 2 cards. I've tried shorting the presence detect pins.
Funny thing is it's not a particular slot or card, it's the total amount of cards. If I have both in the 1x slot both of those will run. If I have one  x16 and  one x1 those two will run. It seems that it can only run the first two cards. I even tried taping the cards down to x1 and plugging that into the x16 slot but it didn't help.
Anyone encountered this or fixed it before?

[ssateneth]

Could possibly be motherboard power issue. Have you tried supplementing the power draw form the motherboard with a molex's 12v? There's a ribbon cable that has a molex connector to supply 12v power.

Also didnt bother looking up the board, but I thought early PCI-E boards were really finicky when it came to spreading bandwidth across multiple slots (Like 16x-1x-1x-1x single card and 8x-0x-8x-0x if doing crossfire/SLI)

[pandemic]

Check for motherboard BIOS update
What PSU are you using? What cards?
What OS?

Try also running CCC 11.7?

[cirz8]

Elaborate on "can't get it to run".
What exactly happens, and what doesn't.

Using PCI-E extenders?
Verified that they are actually working?

Could be a power-issue, single-rail PSU?
If multi-rail, be sure you're not putting too high load on individual rails.

[Yanz]

Not a power issue, using a Corsair TX850 (single rail), all 5850 Xtremes.
I don't think it's a driver issue. The card spins up but won't show up in lspci or AMDOverdrive with -h to list cards.
Running LinuxCoin final.
I don't think it's a bandwidth issue, I downplugged all the cards to 1x and verified they independently work.
There is no BIOS update available.

[Elder III]

Are you using crossfire cables on any of the GPUs?

[Yanz]

Nope. No crossfire cable or dummy plugs.

[pandemic]

check BIOS settings?

[Elder III]

Nope. No crossfire cable or dummy plugs.

Give em a try (not at the same time), may not be an issue, but it's a quick and easy thing to try out.

[Yanz]

check BIOS settings?

I went through every menu, didn't seem to be anything related...is there something specific in mind?
Nope. Dummy didn't do anything, nor did the crossfire bridge.

[Beta-coiner1]

Might want to check your mobo manual on if there is an issue with a multi-gpu setup,usually it is in fine print.A good idea is to update your bios as well as that could be the issue.

[Yanz]

Checked manual. Nothing related to maximum number of cards. Just how to install CrossfireX graphics. BIOS is latest.

[ssateneth]

Still the only thing that comes to mind that may be the problem is the board is unable to assign bandwidth to -all- lanes due to the 16x slots being used. My theory stands that when both PCI-E 16x slots are using 16x PCI-E lanes each, the chipset/bios/whatever "turns off" the PCI-E 1x lanes so the 16x slots can have 16x bandwidth.

This may be something better suited asking a professional on asus forums too.

Could you try 1 card in the main 16x slot and 2 more cards in the 1x slots? If you did this already, I didn't know.
Also most motherboards will post something on the second screen (The one before it loads windows but after the one that shows your memory and hard drives) showing what devices are connected. Verify that it's actually a board issue (doesn't show up in that device list) and not a windows issue by seeing if 3 video card devices are connected there.

[Yanz]

It can't be a bandwidth issue because I downplugged the cards to 1x and only the first two show up. The order is 16-1-1-16. If I do 1x and then 16x video shows up on the 1x adapter. I'm not running windows. But I don't see anything on the post screen about video cards...

[MelMan2002]

Some people have reported problems with >3 cards on a 32-bit OS.  Are you using a 64-bit OS?

[mike678]

Some people have reported problems with >3 cards on a 32-bit OS.  Are you using a 64-bit OS?

I have a rig with 5 cards and its running win7 32 bit. It works fine.