4x GPU one GPU not showing up at all

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headmaster200

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May 3, 2013
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I'm running 4x GPU's on one motherboard and everything is working fine except that one card is not showing up in the system at all, not in the device manager nor in MSI kombustor or afterburner.

I'm using risers for all cards and have now tried everything, changed riser for the card, changed molex connections ( the card is connected through molex adapters )

The problem started when I was trying to switch the power source for it's molex adapters to a seperate molex cable, as I though that might help load on system ( not sure at all, just wanted to try ). The system had then previously worked fine with 4 cards but was freezing at some times which it should not.

Then after changing the molex power source to an own cable I could first see that the card was recognized but without temp and fan speed, and the next time at startup there was nothing, and has not been since then, even after all the experimentation with changing risers / slot.

My specs
Motherboard: Gigabyte 990XA-UD3
GPU's : 4 x 7950 Gigabyte with 7970 accelero extreme coolers installed on them
PSU: Corsair 1200W

Edit: here is a photo I took of how it looks, it's the card closest to the camera which is not recognized http://postimg.org/image/5qj76ht5r/
Also, on one occasion before I had this problem the system suddenly showed 511 celsius on the card that's not responding now, which is totally crazy and of what I assumed was a bugg as the figure did not move, soon after the system crashed and I restarted. Can not really remember if that's when the problems started but it is strange as all cards are running at below 70 celsius at full load.

I can also add that when the 4 cards were connected the system was a bit slow, it took time to connect to get processes started but now when only at 3 cards it's as fast as I've always remembered it to be.

Thanks in advance! :)
 
Solution
ingtar33


YES YES YES. 1000x yes. Please remove that anti-static platic ASAP. That anti-static plastic conducts electricity. and likely is part of the intermittent shorting/power problems you're having. It's like resting them on tinfoil.

Well not that bad but close.

As i was saying earlier, the way those bags work is they actually conduct electricity and form a Faraday Cage (that's the effect where a...
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ingtar33

ingtar33

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Dec 17, 2012
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if you pull one card out (a working one) does the system detect the non-working one? If you move the non-working one to a working port does the system detect it?

sidenote: just looked at your mb manufacturer. it doesn't support 4 way xfire

in fact it only HAS 3 pci 2.0 (and supports two way xfire); how did you plug in a 4th card?
 
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headmaster200

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I'm connecting all the cards with risers.

Previously when it worked i had

3 cards on x16 risers, 1 card on 1x risers.

Now when not working, after all kinds of testing

2 cards on x1 risers, 2 cards on 16x risers.

The nonworking card is on a 16x riser.
 
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bignastyid

bignastyid

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I'm guessing he is using a 1x to 16x adapter for the 4th card which is going to bottleneck it's performance horribly.
 
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headmaster200

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This is just so crazy!

The system suddenly crashed ( why I don't know, controlling it though teamviewer from another computer and saw that the computer was logged out and couldn't reconnect to it ). So force-shutted it down and now when I started it it shows all 4 card?! WTF

Have had these problems before with not recognized cards or black screen on bootup and the solution every time seems just too odd, or it just strikes one from heaven one day.
 
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bignastyid

bignastyid

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You have 2 cards running at 8x, 1 at 4x and 1 at 1x. Running them like that is a waste of potential. the card in 4x slot will be slow and the one in the 1x slot is crippled and pretty much worthless with the bottleneck, Plus the board was never meant to run 4 of those cards, Im very surprised it even kinda worked in the first place.
 
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zyky

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Have you tested the one card by itself, no risers? Seems like a dud card to me.

I'm considering getting 20 7950s myself.. I should probably brace myself for the chances I'll get a few bad cards myself.

BTW, How many MH/s were you getting? (Per card/total)
 
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headmaster200

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I did some overall testing on the whole system, tried to press every card on full load 15 min between each other.
Unfortunately the third card connected with molex adapters got one of the molex's melted off... ( a dangerous sport indeed ). http://postimg.org/image/pkebtqevb/ Does someone know why this happened? Would this be avoided if one placed the molex connector on a seperate line of molex adapter ( i think it's called ) from the PSU?

Got only to test to run three cards at full load, so never tried four.
Pretty bad if one is not able to go for 4 cards, I see this as an quite heavy investment and a framework for my other coming rigs, and missing one card on a motherboard costs quite alot.

I noticed that the system ran fine, but there was considerable delay. Took like 4 sec more to start a load on one of the graphics card when having four than compared when having 3 cards.

For the one's also mining

I'm mining litecoin, seems to have more investment potential according to me. Also I'm getting 600 khash/s/card at litecoin, which is fully normal.
I can recommend building the case in wood unless you don't have access to a milk crate or something which has a perfect fit, it's very (!) cheap, built mine for around 10$ excluding tools. Just wrap the bar where the cards actually touches the wood with antistatic plastic which you've saved and you should be fine from any potential fire.

Also the Accelero xtreme 7970 aftermarket coolers are really good and might be a worth looking at, none of my cards have exceeded the 75 celsius mark at full load. And also they produce way(!!) much less sound than the stock coolers.

I noticed that when having 4 cards connected, the stale/invalid rate on GUIminer were much higher than normally. I normally have around 1% stale ( using stratum ), now the stale rate was around 5-7%, still OK but would be nice to know what's causing it.


Edit: where can one see what the motherboard supports in terms of multiple PCI-e connections in the manual? Could not see it.
 
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ingtar33

ingtar33

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yes. that happens when your PSU is junk, or unable to handle the voltage it's pumping out safely.

Corsair makes solid psus... but i fear this whole rig is at the edge of what your psu can manage safely. you might start an electrical fire and destroy your rig if you don't find a different/better psu.

my first guess at the problem seems to be spot on... this whole rig is overtaxing your 12V rail on your psu. you need a psu with a more robust 12v rail then this one.
 
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ingtar33

ingtar33

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remember the overall wattage of the PSU doesn't matter. What matters is what the 12V rail can handle.

a faulty psu from the factory can ruin a perfectly good psu that normally could handle the load. i'm sure this psu is right up against what it could normally safely manage, if something is a little faulty you get a breakdown.

I'd return the psu, tell them it started an electrical fire and get it replaced. if others are safely using that psu with that build then it's likely just defective.

i'd also look into better risers... the fact that they only work intermittently makes me wonder if they're grounding out something... which can cause a short and break stuff.
 
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headmaster200

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First of all, thank you ingtar33 and others for all your help. Much appreciated!

I see, yes I will definitely consider doing that. On the other hand, do you think having a splitter like: http://www.ebay.com/itm/290778077889 instead of the molex adapters would resolve the issue? Would be very convenient for me now when I don't really trusts molexe's any more.

What you mention about the risers is interesting, in fact I just had some crashes for no reason. The motherboard is on top of some antistatic plastic covering the whole motherboard and more, but right now I've not experienced any crash for a period. What do you mean with grounding?
 
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ingtar33

ingtar33

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well... since you're making your own bench... its not beyond possibility your system is grounding out into something behind your motherboard. generally speaking nothing should be touching the back of the motherboard... and the motherboard should only be screwed into the "tray" at designated points.

your symptoms scream power problems... or possible hardware issue with the mb/spacers.

i'd make sure your system is stable with no grounding issues by backing everything down to the onboard graphics and see how stable the system is under a prime95 test (10+ hours).

then i would put in each gpu, one at a time, and run a gpu stess test like Furmark for a few hours on each gpu, one at a time.

assuming your system is stable we'll know that the mb/gpus are fine. now when you crash we'll know it's either the psu or the spacers causing the problem. My money remains on the psu. That a molex plug melted tells me something serious went wrong with your psu somewhere.


SIDENOTE: just noticed you're resting your mb on the anti-static plastic bag. those bags CONDUCT ELECTRICITY. That is likely what's grounding out your motherboard. Pull that out from under the mb immediately before you blow something up or start an electrical fire. with luck you've not damaged something permanently.

the anti-static bag forms a Faraday cage... which means they protect anything INSIDE the bag from electric shock. they do nothing for anything outside the bag. frankly they conduct electricity way too well, so please listen to me and remove the bag asap.
 
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headmaster200

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Thank you ingtar33. I really had no idea about this, will change it immediately.

Do you think I need to change the antistatic plastic which all the gpu's are resting on? I've covered the wooden bar which they rest on ( seen in first picture at starting-post ) with antistatic plastic, don't know now if that's such a good idea.
 
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ingtar33

ingtar33

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Dec 17, 2012
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YES YES YES. 1000x yes. Please remove that anti-static platic ASAP. That anti-static plastic conducts electricity. and likely is part of the intermittent shorting/power problems you're having. It's like resting them on tinfoil.

Well not that bad but close.

As i was saying earlier, the way those bags work is they actually conduct electricity and form a Faraday Cage (that's the effect where a metal frame is actually a naturally grounded form)... the result is any static buildup or even electrical charge WITHIN the bag is grounded out and no harm comes to the product.

The problem is outside the cage, there is no such effect. You're basically resting your boards on a moderately conductive material which either shorts out your part or promptly grounds it out. worse, by damaging the structure of the plastic bag (by cutting it up into sheets) you remove the "cage" and all you're left with is a non-grounded conductive material, which will short and burn out all sorts of electrical parts.

please, remove all those anti-static bags before you damage something irreparably.
 
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Solution
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headmaster200

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Update from my note.

Installed the motherboard on a plexiglas and everything is working absolutely great except a strange issue ( started another thread regarding this ).

Thanks to ingtar33 for all help, best solution picked.
 
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