Silly 7950 crossfire issues

Tarvaln

Senior member
Apr 28, 2004
310
2
81
PC specs are in sig.
I got a second 7950 to go with the one in my sig. Only difference is the new one is a Sapphire 3L

Running 13.8 beta 2 drivers from a clean install. I uninstalled old drivers, ran driver sweeper twice, then installed new drivers. As far as I know there are no bios settings for dual GPU but the documentation for that is hard to find.

I've had two issues with it.

First. In GPU-Z the second card is always shown as PCIe x16 @ x1 (not @x16 like my mobo is suppose to do). Cards are installed on first and third PICe slots as my mobo manual recommends. I've run the GPU-Z shader test to see if the second card will get a different reading. Ran the test for 10 mins at full screen. Second card stayed at PCIe x16 @ x1.
2wmq97n.jpg


Second the second GPU is always at 99% at idle. I don't think this is a read error due to the temp also being higher than the first card. I read this may be due to the beta driver.
FIXED! I used Sapphire Trixx to disable ULPS. My card now powers down when idle
a9qq9d.jpg


When I disable crossfire the second card goes to 0 load and 300 mhz Core Clock

Any idea on why I'm getting these number and what I can do to fix them?

Thanks.
 
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BallaTheFeared

Diamond Member
Nov 15, 2010
8,115
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See if this helps your usage issue:

Capture_zps3bafb4f4.png~original


As far as the lane bandwidth, did you run the test from GPUz in fullscreen? If so you might want to try another PCIe slot.
 

Tarvaln

Senior member
Apr 28, 2004
310
2
81
Yea Bella, I did run it at full screen.
Using Sapphire Trixx I disabled ULPS. My card now powers down when idle. (Thanks!) I also enabled "Synchronize cards in Multi-GPU config" though I doubt that changed anything.

I'll try the port swap later. My mobo manual said to use first and third port because they are suppose to be at @x16 for each. In theory if I use the second port it should put that card at @x8.
 
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Black Octagon

Golden Member
Dec 10, 2012
1,410
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Try a single card in the offending PCIe slot to be sure that the problem isn't with the slot itself. If it shows the correct x16 when that's the only card in the system then you can continue troubleshooting in confidence that the issue has something to do with the presence of 2 cards in the mobo at once (and/or drivers).
 

BrightCandle

Diamond Member
Mar 15, 2007
4,762
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Its possible that the motherboard has settings for the number of PCE-E lanes assigned to the slot, some boards do. Many just auto select when cards are put into them but that isn't how they all work. Take a look in your manual, its likely going to contain detailed instructions about how to set crossfire, including the slots to use, any bios settings needing changing, bridges and driver installation.
 

thilanliyan

Lifer
Jun 21, 2005
11,848
2,051
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Look at the current issues in the release notes for the 13.8 b2 driver. I thought I saw something about the PCI-e speed.
 

Tarvaln

Senior member
Apr 28, 2004
310
2
81
Thi, Saw this in the driver notes

· CrossFire configurations (when used in combination with Overdrive) can result in the secondary GPU usage running at 99%
· Enabling CrossFire can result in the PCI-e bus speed for the secondary GPU being reported as x1

I think that is my problem. If you look at the pic I posted, you notice that even though the says the card is running @x1 the Bus Width and Bandwith are the same as if you are running it @x16. I'm decently sure if it was really running @x1 those numbers would be lower.

I'm pretty sure my problem is solved. Thanks to everyone that posted. That's why I like these forums. People are really helpful here.
 

Riceninja

Golden Member
May 21, 2008
1,841
3
81
you have both the 2L and the 3L right? do you find the 3L that much worse? im thinking of getting another one too, too bad theres no more 2Ls...
 

Tarvaln

Senior member
Apr 28, 2004
310
2
81
What do you mean by "that much worse"? If you mean in terms of overclocking, I haven't pushed my card past 1050/1250. I'm don't want to overvolt so I'm not sure if I can do 1100 with that. Also, for some reason my 2L card does not like it's memory pushed any higher. If I do after about 10 mins the image on my main monitor will scramble. Not sure why but, I do know there are other people with the same problem. I haven't overclock either card since I put the second one in.