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I've not had any luck at all getting 3 cards working. All 3 cards are known working, all risers tested good (powered x1 to x16).

ASRock 970 Extreme 4
3x Asus R9 290
Windows 7
850W Corsair 80+ Gold PSU (running 2 cards atm. when I tried 3, I also added another 750w PSU)

I can't get windows to see a 3rd card. I've tried shorting presence pins (which makes me nervous, I want to avoid that all together. seen lots of horror stories on it.) which didn't help either.

I've re-seated them in every way possible (using risers, at least.)

Only thing I can immediately think of that I have not tried is leaving 1 plugged into an x16 on the board.

Thoughts? Should I just break down and buy some x16 to x16 risers and try them out? Anyone else successfully running this (or a very similar) rig? For now I had to pull out my 3rd card and put it in my gaming pc (closed case, nvidia main card, not ideal at all)

I have a similar rig. 3x Gigabyte R9 290s on an MSI MB. 2 of them on 1x powered risers, 1 on the MB. Could it be that you need to have one on the board?

I had a rig with 3 R9 290s up and running successfully before I swapped the cards out (hated the noise).  If you're just using the 850W power supply, you don't have enough power, guaranteed.  If you're using the additional 750W, this shouldn't be a problem.

Have you tried connecting an HDMI cable into the third card that feeds into a monitor?  I find that sometimes, it's needed to force recognition.  With three cards in the PCI-e 16x slots, you shouldn't have to use jumper cables at all.  Also, I'm assuming you're using the latest drivers and you've installed the proper ATI SDK.

Another thing to check is to ensure that Crossfire is disabled.

thanks for replies guys

i have a monitor attached currently mining w/ 2 cards so its not crossfire settings. with 3 cards i use both psus. i'll try putting one card directly on the motherboard and 2 others on 1x powered risers.

@grippy54 do u use your 1x powered risers in 1x slots, or the beginning part of your x16 slots? my board has 3 x16 slots and 2 x1 slots.

I have a 3x R9 290 rig and one of my cards is plugged directly to the x16 slot (waiting on a x16 to x16 riser) and the other 2 cards are with powered risers connected to the x1. I am also running headless.

Did you actually check to make sure that Crossfire isn't enabled?  It sounds like you're assuming that it just isn't, but it enables itself by default.  The R9 290s use software Crossfire and don't need a bridge.

I put the 1x risers in 1x slots.

i will go try putting 1 card in the first x16 slot directly on the board and the other 2 in 1x slots on powered risers. thanks for all of your replies guys.

@minerman1234: how does one disable the software crossfire? i've always been an nvidia card user for gaming and i was unaware that r9 290s ran off of software crossfire. i don't see any options to disable it in CCC though.


i will edit the bottom of this post w/ results

i tried running 1 card on the mobo w/ 2 on powered risers. no luck.

tried running 2 cards in x16 slots on the mobo w/ 1 on a powered riser, also no luck. literally every 3-card configuration i can come up with does not seem to work. what gives!?

Not really sure what to suggest. It wasn't really anything difficult to get my hardware working. There were no special tricks. Could it be something with your motherboard? Check in the bios settings to see if anything jumps out at you.

nothing in bios that looks like it could be even remotely related

How much ram you got in there? I would suggest 12gb for 3 290's to be sure its not the issue. 4gigs will NOT work, you might get away w 8gb.  Also, I'm assuming you reinstalled the latest ati drivers after plugging em all in? Also, I forget if 290's have dual bios switch's, maybe u flipped one by mistake?
Do all 3 cards work independently? It will take some time but check all cards one at a time, then check all slots. Hope you get em running, ive had similar issues & its fu*king annoying esp when u've spent mad cash on em!

ive tested all cards individually. ive tested all 4 (i bought an extra) powered risers individually. ive tested every imaginable combination of 3 cards and simply can't get it to take. i legitimately am out of ideas

how much ram you got installed on the motherboard?

8gb. i've seen guys running 5-6 cards with 8gb i don't think that's an issue at all.

i have mixed gpus in one of my rigs, a 290x, 270 & 2 8750's, only a couple cards would work with 4gb system ram, after adding another 8 they all started, i could be wrong, but it couldn't hurt to add another 4gb if you have an extra slot & a stick of ram... or even spending $40 on a stick, better than your $$$ sitting dead.

it's not sitting dead, i have it in my gaming pc. but it's not ideal, since my gaming pc is nvidia based. even getting both drivers installed at once was kinda hectic.

Not needed. I'm running a 3x R9 290 setup with only 4GB.

@OP - You never mentioned it (and no1 asked either), but which version of Windows 7 are you using? If you're using 32bits than it all makes sense (it's cant detect more than 4 cores) and you'll need to install Windows 7 64bit for your 3rd card to be detected.

But in case you have 64bit, let's go back to the basics: When you plugged the cards one by one they all worked solo, yes?
You tested every PCI-e slot (those you will want to use) with a single card in the system?
You shorted the pins correctly? (A1-B12)
Did you set up the 2nd PSU correctly? (make sure you don't mix the 2 PSUs).

Right now I can't think of anything else really, other than to get a x16 to x16 riser and try that out.

When I set my rig it was pretty straight forward. I connected 1 card (to the x16), installed drivers+sdk, tested, saw it worked, went on connecting the 2nd card (to the x1 with powered riser), saw it worked, moved to the 3rd card (also to x1 with powered riser) saw it worked and that's about it.

I tested each card individually, checks good.
I tested each riser individually, checks good.
I tested each pci-e slot individually, checks good.
I have not shorted the presence pins, I've seen a lot of horror stories about it working but frying the mobo within a week. I'd like to avoid shorting pins by any means.
For the second PSU, I shorted the power wire to one of the ground wires on the 2nd PSU. I plugged the video card in to the PSU. I kept all my powered risers on the same PSU (perhaps this is my problem?? should I isolate the 1 card, riser included?).
I don't see how a x16 to x16 riser would behave any different from plugging directly into the board.

For the record, what kind of mobo do you have? At this point I'd be willing to just buy a new mobo to avoid this headache. This board is honestly shit from my current experience.

Gigabyte MA790FX-UD5P.

Anyway, again, which version of windows do you have?

BTW, when you turn on the PC with 3 cards in it, do the fan(s) spin on the 3rd card? (the one Windows doesn't detect)

windows 7 home prem. 64bit

yes the fan spins on all 3 cards.
system information appears to recognize 3 cards are attached to pci-e slots.
device manager however disagrees, and only shows 2.
cgminer agrees with device manager, and only hashes w/ 2.


repeating an old question although it hasn't been brought up in a while: how do i disable crossfire? i was told it's software crossfire, no jumper required... and that it's on by default.

Not sure about how to disable Crossfire, but! I do remember I needed to disable ULPS (Ultra-Low Power State), what it basically does is disable cards that are not in use, so by disabling ULPS you make sure that all cards work at all times.

To disable ULPS:
1. Go to the registry ("regedit" in windows search - make sure you open it as admin).
2. Make sure "Computer" is highlighted and than go to Edit -> Find -> EnableULPS
3. Double click on EnableULPS on the right side and change its value to 0 (Hexadecimal base).

Restart PC and check to see that the registry was saved (again, make sure you access regedit as administrator).

I had the same issue temporarily. 1 card didn't seem to like the 1x to 16x riser in the 16x slot. Plugged it directly into the mobo and then no probs.

If all 3 cards fit (they do on my mobo) did you try putting all 3 directly onto the mobo? (temporarily of course)

value of 1 would be on. i set it to 0 and i'll try it out in a bit. hopefully this works






i dont think all 3 cards fit. haven't tried since it would be unrealistic to use 3 290's all unpowered (or at least that is my assumption)

Yes yes, my mistake, I meant to type 0 there.