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Crossfire a 6850 with x16/x4 a bad idea?

Last response: in Graphics & Displays
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November 4, 2010 7:22:49 PM

Ok so I have a problem. I have a HAF 922 Case and I have 2 x8's, 1x16 and a x4 slot

Problem I'm having is one x8 slot is right under the x16 slot and I can't stick a card in there. The other x8 slot is all the way at the bottom and the power supply is blocking any card I want to put there. The only solution I have is to stick my second card into an x4 slot. Is that not worth it for a 2nd 6850 or is there a better case that would help solve this problem?

Best solution

a c 600 U Graphics card
a b ) Power supply
November 4, 2010 8:48:17 PM

"The Bottom Line
The results are actually a bit shocking to us to be honest. We weren’t so surprised that in the previous evaluation x8/x8 did not cause any differences at 2560x1600 but did at 5760x1200. However, we thought certainly at x4/x4 PCIe 2.0 mode there would be some kind of a bottleneck at 2560x1600, but the results have proven otherwise. Even with all the data that GTX 480 SLI is pushing across the PCIe bus, x4/x4 is NOT a bottleneck in a single display setup at 2560x1600 with AA enabled. The only game to show us any difference was AvP, but it did not affect the gameplay experience. Therefore, if you are on an aging PCIe 1.X system at x8/x8 mode (equivalent to PCIe 2.0 x4/x4) on a single display fear not, you are not holding back the performance of GTX 480 SLI or we guess with any CrossFireX or SLI configuration."
http://www.hardocp.com/article/2010/08/25/gtx_480_sli_p...
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a b U Graphics card
November 4, 2010 9:33:55 PM

What m/b do you have OP. Usually they arrange these things, SO YOU CAN, put two double slot cards in a dual gpu config.
Sometimes its without a slot, in between. May not be ideal but it works.
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November 4, 2010 9:35:11 PM

Part Number: 141-BL-E757-TR
Part Desc: EVGA X58 SLI LE
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a b U Graphics card
a b ) Power supply
November 4, 2010 9:38:30 PM

SLI is different from crossfire, and with X4 bandwidth, crossfire tend to take a performance hit.

However, why dont you just use the first 2 PCIe slots? It will fit fine.
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November 4, 2010 9:39:32 PM

I could try but it might be pusing it. It'll be hard to get it to fit that close. Also its a X58 board. Just advertised as SLI but it does Crossfire too.
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a b U Graphics card
a b ) Power supply
November 4, 2010 9:41:37 PM

The 6850 with open coolers should be just fine. Its only takes up 2 slots.
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a b U Graphics card
November 4, 2010 9:42:00 PM

I would put it in the x8 slot.
It does not leave any slot between the 2 cards, but thats not uncommon.
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a c 600 U Graphics card
a b ) Power supply
November 4, 2010 10:49:22 PM

Wait, if that is an X58 mobo, it should natively support two x16 PCIe lanes. Why do I only see one? Is it because it is the LE (low end) model?
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November 5, 2010 12:13:28 AM

Wait le means low end? I thought it meant limited edition
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a b U Graphics card
November 5, 2010 12:18:29 AM

I believe that LE , in this case means - light edition.
The X58 chipset supports a total of 40 pci e lanes.
But the m/b manufacture still has to build in switching controllers which cost 'money' to enable various pci-e lanes for the physical slots they include on the board.

In this case they chose, electronics ,and a bios to support only 16x-8x
It could be worse, some make this scenario 8x-8x

They use this as a pricing positioning tool within their own board lineup.

edit: light edition specifications correspond with the micro-atx format which this board is.
Because of its size and intended usage, possibly HTPC cases , which are smaller. The overall intended 'usage' of this board is scaled down. That applies to overclocking prowess also.
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November 5, 2010 12:20:57 AM

I hope it doesn't get too hot with one card blocking the fan of the other.
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November 5, 2010 12:22:23 AM

Wait its standard atx not micro atx
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a b U Graphics card
November 5, 2010 12:24:18 AM

Metroidman said:
Wait its standard atx not micro atx

My mistake , thought it was a micro board :) 
http://www.amazon.com/EVGA-141-BL-E757-TR-X58-SLI-Mainb...

Quote:
Product Description
The X58 SLI Motherboard from EVGA is designed for the win. Featuring EVGA VDroop control for maximum voltage stability while overclocking, Onboard Clear CMOS, Onboard power and reset buttons with built in power and hdd activity led indicators, EVGA E-LEET tuning utility which provides quick access to overclocking controls without going into BIOS, and onboard Debug LED's for current CPU temperature reading, your system will be able to handle the latest games, high definition digital video, and Windows Vista with aplomb. Additional features of the 141-BL-E757-TR include support for Intel Core I7 processors, Intel X58/ICH10R chipset, 6 DIMM Triple Channel DDR3 up to 1600MHz, Enthusiast Layout supporting 2-way SLI, 3-way SLI with PhysX, 6 SATA II 3 GB ports, Gigabyte ethernet port (10/100/1000), 8 channel audio (includes COAX and optical), 12 USB 2.0 ports (8 I/O, 4 External), 2 1394 external Firewire slots, and passive heatsink. Product comes with a 1 year warranty and a second year free if registered at www.evga.com within 30 days of purchase
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a c 376 U Graphics card
a b ) Power supply
November 5, 2010 12:25:55 AM

Timop said:
SLI is different from crossfire, and with X4 bandwidth, crossfire tend to take a performance hit.

Do you have any data on that?
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November 5, 2010 1:14:27 AM

I hope its not a huge performance hit
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November 5, 2010 2:03:31 AM

So is xfire really bad on x4?
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a b U Graphics card
a b ) Power supply
November 5, 2010 2:08:56 AM

jyjjy said:
Do you have any data on that?

Note the P55 Tri-fire which is x8/x8/x4

On the Mobo, the LE just denotes lighter features, the X58 NB did not change. Its X16/X8/X8 is because EVGA split up the second X16 lane into 2 X8 slots for Tri-SLI.
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a c 173 U Graphics card
a b ) Power supply
November 5, 2010 2:09:00 AM

The problem is not the lane count but the actual bandwidth that the cards receive between them and access to the cpu. You may be able to saturate this link but you won't be scaling as well as those who have 8x8 or better. The problem is the mirroring of data between both cards is that one is going to be slightly lagging behind the other so you will lose what you would have normally had in terms of gains so being highly conservative that you should expect 40-60% instead of 90%.
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November 5, 2010 2:21:42 AM

So stick it in the x8 slot. Would the cards being on top of each other make them overheat?
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a c 173 U Graphics card
a b ) Power supply
November 5, 2010 2:54:55 AM

You can force air between them if you know what you are doing.
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November 5, 2010 2:56:26 AM

nforce4max said:
You can force air between them if you know what you are doing.



How's that? Would that be a better solution?

I was also considering a different case. Any case that would solve this problem that's not super expensive?
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a c 173 U Graphics card
a b ) Power supply
November 5, 2010 3:00:34 AM

Metroidman said:
How's that? Would that be a better solution?

I was also considering a different case. Any case that would solve this problem that's not super expensive?


It depends on quality and taste, I ended up using an 11 year old rust bucket simply because it was easy to manage cabling and cooling plus it was free but for you try looking around I am sure that you might find something that isn't to bad that is cheap. You can try making some custom mounts for a spare case fan or two and keep your current case instead that will cool the cards.
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a c 376 U Graphics card
a b ) Power supply
November 5, 2010 3:42:31 AM

Timop said:
Note the P55 Tri-fire which is x8/x8/x4
http://media.bestofmicro.com/8/V/234895/original/image029.png
I don't think you can just generalize from triple crossfire results to dual crossfire. Going in the opposite direction techpowerup did an article showing a x4 slot only limits an HD5870 by about 5% on it's own.
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November 11, 2010 11:03:17 PM

Ok well I got the Lian Li K62 Case which has 8PCI Slots and I can now fit my new 6850 in an x8 Slot without blocking fans

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November 11, 2010 11:05:19 PM

Best answer selected by Metroidman.
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a c 271 U Graphics card
a b ) Power supply
November 11, 2010 11:15:59 PM

This topic has been closed by Mousemonkey
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