Hi there,

I've added a second GTX570 to my machine but for an unknown reason, this second GPU is very slow compare to the other one.

For example, a I13R7-NATHAN_CB1 will take 8h35 on the first GPU but 12h31 on the [ur=http://www.gpugrid.net/result.php?resultid=5251012l]second GPU[/url]...

BOINC recognizes well the 2 GPUs and I have a cc_config.xml that includes:

(Temps are much lower as well on the second card)

Hi Zydor.

- No SLI enabled (And I didn't find any option in the BIOS)
- 25 degrees differences between the 2 cards

and I've updated my Nvidia drivers to 295 version.

No difference.

I will try to swap the card, but I guess it will be the same thing....the second one will be slower....

Any other idea?
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MyUneo, the Cupid of Services

If you could post your FULL system specs, it would help out immensely(think I spelled that wrong). mobo, psu, cpu, everything.

Second card is cooler cos it has less to do it seems. Whats gpuz says?
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DSKAG Austria Research Team: http://www.research.dskag.at

I will try to swap the card, but I guess it will be the same thing....the second one will be slower....

Any other idea?

No difference when swapping the cards.

And as I said an update of the driver didn't change anything.
Could it came from Xorg settings or so?

Actually...it has always been an issue... When I had 2 GTS250 into another computer, the second one was slower....funny, after 2 years, still the same issue ....

I could try an update GNU/Linux version (Like Sabayon/Fedora/Ubunutu) but doesn't seems the good way to me.
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MyUneo, the Cupid of Services

Both cards are on Maximum performance...
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MyUneo, the Cupid of Services

Same reason why i asked for specs.

EDIT: Well scratch that actually, although I first though PCI, which it still could be, it wouldn't be in the sense that since i7 2600k can support 16 lanes, meaning it couldn't be x16+x4 since that would be 20 lanes. For the numbers to work out the way they do, it would have to be like x12+x4, which isn't possible if I'm not mistaken.

EDIT2: Since it SHOULD be x8,x8. Do you have any other PCIE devices plugged in? Such as networking cards, sound cards, etc.?

My MB is a Gigabyte GA-PH67A-D3-B3 and I don't have any others PCI slot used.

Thanks for your help !
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MyUneo, the Cupid of Services

I believe it is a PCIE slot issue based on your mobo specs:

1.1 x PCI Express x16 slot, running at x16 (PCIEX16)
* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.
2.1 x PCI Express x16 slot, running at x4 (PCIEX4)
* When the PCIEX1_2 or PCIEX1_3 slot is populated with an expansion card, the PCIEX4 slot will operate at up to x1 mode.


What this means to me, and I am personally just learning about lanes and PCIE issues with CPU and motherboards, BUT from what I can tell, your first slot has the capability to run at x16, and your second one at x4.

However, since the second slot cannot run at x8, this prevents your GPUs from being even at x8 and x8 respectively. Since 1155 CPU can only operate x16 lanes at a time, you are most likely running at x8 and x4. Since your second slot cannot go up to the x8 that your CPU can support.

This would be my best guess. As stated above, since 2 are in, i WOULD ASSUME that your CPU is trying to go x8+x8, but your mobo does not allow it, so it defaults to its own settings of x8+x4.

Skgiven: What am I missing here in regards to the PCIE lanes. If 1155 chips can only operate 16 lanes, than how could it be possible for his cards to operate at x16 + x4. This does not make sense to me. It would be impossible(?) to run at x16+x4 on an 1155. Right?

On the other note. Yup, different clock speeds and tasks will definately(probably) account for that discrepency. lol, guess we should have looked at that first!! ;)

Again, what am I not understanding about PCIE lanes?

http://www.enthusiastpc.net/articles/00003/2.aspx. From the way I read this it's 16 lanes unless the motherboard has a special chipset. Is this correct? I really think the sb and ib only support 16 natively

Ah...
In fact I think I've been confuse with the :

# Approximate elapsed time for entire WU: 13691.716 s
08:35:49 (12888): called boinc_finish

08:35:49 is not the runtime...

I see now why in term of point I don't see much difference.

So all goods in fact, I might loose 5% from somewhere, but no harm.
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MyUneo, the Cupid of Services

Thanks skgiven for this extended explanation!
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MyUneo, the Cupid of Services

Just to further illustrate Intel's dominance. PCIE 3.0 has been recently disabled on the 680 drivers for the SB-E x79 platform. (besides the one that came with the device, like 300.86) This is because when the x79 came out and SB-E chips came out, there were no devices to test them out on. If you look at the 2011 CPUs, they will say PCIE 2.0, with the ability to have 8GT/s. Since they could not validate the PCIE 3 compatability. So NVIDIA disabled PCIE 3 on their latest drivers for the 680, since Intel says nothing is "Validated".

Now, NVIDIA is having to certify motherboards that work with PCIE 3.0, even though they worked when they first came out. People have done registry edits, and then showed using GPUz that PCIE 3.0 is indeed working.

It's all because of Intel saying that everything needs to be certified and validated.

Of course though their motherboards (x79) show the ability to have PCIE 3.0, yet their chips say 8GT/s. All "stupid" semantics as far as I'm concerned.

AMD 7000 series are of course showing PCIE 3 on their GPUs on x79, but this is because they probably don't have to listen, nor care about Intel as much IMHO.