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Message boards : Graphics cards (GPUs) : P35 Board better than SLI 750i ?

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Rantanplan
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Message 22207 - Posted: 3 Oct 2011 | 16:30:06 UTC

Hello,

will a newer chipset mainboard give me a speed

advantage to compute with two gpus on one mainboard ?

What will be the advantage ?

Thx.

Profile Retvari Zoltan
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Message 22208 - Posted: 3 Oct 2011 | 21:56:30 UTC - in response to Message 22207.

The P35 chipset is not (much) faster than nForce 750i SLI. Both have only 1 PCIe x16 channel, so if you put 2 GPUs in one mainboard, both will run only at x8 with any of these chipsets.
If you want speed advantage, you need multiple native PCIe x16 slots, which will work at the x16 speed even if you populate all PCIe slots. Motherboards based on the Intel X38, X48 and nForce 780i SLI, 790i SLI chipsets, have 2 native PCIe 2.0 x16 slots.
You can achieve about 8-15% speed gain (depending on the WU type) compared to nForce 750i (or P35, P45) mainboards running with two GPUs

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Message 22209 - Posted: 3 Oct 2011 | 22:13:15 UTC - in response to Message 22207.
Last modified: 3 Oct 2011 | 23:03:42 UTC

As discussed here it would in part depend on the PCIE speeds.
The SLI 750i chipset offers dual x16, but that might not always be the reality for every motherboard.
Some P35 boards offer DDR3 and a 1333 FSB, noteworthy considerations in themselves, but few if any offer two x16 PCIE channels; The Gigabyte GA-P35-DQ6 for example has one x16 slot and one 4X slot. So the question is, would having a 1333MHz FSB and DDR3 (rather than 1066MHz FSB and 800MHz DDR2) offset the loss of 12 PCIE channels in the second PCIE slot?
It also depends on your second GPU. If it's a GTS450 then it might not make much difference, but if it's a GTX580 then it would. My GTX470 was 13% slower on X4, and Zoltan's GTX580 was 20% slower. Rough guess would put the GTS450 at around 8% slower. Of course to benefit from the 1333MHz FSB you would need to use DDR3 and OC your Q6600 to 3GHz, a bonus in itself if you are not already overclocking. So would a 25% increase in CPU speed, FSB and RAM more than offset the loss? Perhaps slightly but perhaps not worth the upgrade.

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Message 22214 - Posted: 4 Oct 2011 | 19:56:52 UTC - in response to Message 22207.

ok , i understand, that doesn´t worth it to upgrade.

But i can search for those boards in future time. Thx.

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Message 22424 - Posted: 30 Oct 2011 | 10:41:27 UTC - in response to Message 22214.

Hello, another question:

Can i get the same performance results, when

i overclock the PCIe frequency of the mainboard ?

Could u help ?

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Message 22429 - Posted: 30 Oct 2011 | 21:25:44 UTC - in response to Message 22424.

Do not overclock the PCIe frequency. PCIe does not tolerate overclocking. You can overclock it at most by 5%, but it may decrease the stability of the PCIe bus, which is crucial for GPUGrid tasks running for hours.

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Message 24319 - Posted: 8 Apr 2012 | 18:10:25 UTC
Last modified: 8 Apr 2012 | 18:29:01 UTC

I have just overclocked my PCIe clocking on my SLI board.

Hopefully it won´t crash :)

I also see a rise in utilisiation on gpu activity , also in wattage as temperature, hopefully it won´t blow up.

I am watching it.

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Message 24325 - Posted: 8 Apr 2012 | 23:23:35 UTC

ok, absolutly no zero advantage by overclocking pcie bus frequency, what a mistake.

i change clockings immediatly.

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Message boards : Graphics cards (GPUs) : P35 Board better than SLI 750i ?

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