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Old 24th Nov 2010, 18:13   #1
Schoieuk
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P7P55D LE Crossfire help

http://www.asus.com/product.aspx?P_I...0Lm&templete=2

This motherboard sais that it can support crossfire

One PciExpress slot is running at 4x but is a 16x slot.

Can any one explain how to set it to 16x or why it is running at 4x atm?

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Old 24th Nov 2010, 18:18   #2
stulid
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Its running at 4X as there is not enough pci-e lanes to go around, the slot is a physical 16X in size but is electrically connected at 4X.

The p55 chipset only has a limited number of these "lanes" to go between all the slots and other control chips.

there is no way of altering this.

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Old 24th Nov 2010, 18:20   #3
Schoieuk
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thanks what sort of difference is there between 4x and 16x with crossfire

Last edited by Schoieuk; 24th Nov 2010 at 18:23.
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Old 24th Nov 2010, 18:28   #4
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The difference is pretty substantial, to the point where it is widely regarded as a waste to try to run Crossfire on this board; although it is advertised as Crossfire ready in reality it is a single GPU motherboard. Possibly for someone wanting a strong single GPU and a lesser nVidia card for PhysX or CUDA.

If you already have the cards to Crossfire with, just try it. It lets you shift between single GPU and Crossfire quite easily, so you can make up your own mind. However if you only recently got it and you want to have an actual Crossfire setup, I would return the motherboard for one that does 8x/8x.
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Old 24th Nov 2010, 18:34   #5
Schoieuk
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ok thanks

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Old 24th Nov 2010, 19:04   #6
Aretenon
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Quote:
Originally Posted by Schoieuk View Post
thanks what sort of difference is there between 4x and 16x with crossfire
I think that the difference gets greater, when the cards being used get faster, so you would have more problems with a pair of 5870s compared to, for instance, a pair of 5750s.
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Old 24th Nov 2010, 20:15   #7
Schoieuk
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Are there any p55 mobos with 2 16 slots? running at x16?

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Old 24th Nov 2010, 20:30   #8
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Quote:
Originally Posted by Schoieuk View Post
Are there any p55 mobos with 2 16 slots? running at x16?
With standard configuration P55 boards the limit is x8x8. However, with the use of an Nforce 200 chip two x16 lanes can be provided from this - so boards using this chip can run dual graphics cards at x16 speeds.

None of these boards are available on OCUK, one example is called the Gigabyte P55A UD7. The main drawback of these boards is the price - they are usually closer to 200 than 100 and the performance difference between dual GPU x8x8 and x16x16 is very small as usually x8 speed is enough for a modern graphics card.

i7 3770K @ 4.5GHz//16GB DDR3//Gigabyte Z77X-D3H//MSI GTX 980//Xonar D1//Dell U2412M x2//Samsung 840//HX 850W
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Old 24th Nov 2010, 20:39   #9
Schoieuk
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Originally Posted by cmndr_andi View Post
With standard configuration P55 boards the limit is x8x8. However, with the use of an Nforce 200 chip two x16 lanes can be provided from this - so boards using this chip can run dual graphics cards at x16 speeds.

None of these boards are available on OCUK, one example is called the Gigabyte P55A UD7. The main drawback of these boards is the price - they are usually closer to 200 than 100 and the performance difference between dual GPU x8x8 and x16x16 is very small as usually x8 speed is enough for a modern graphics card.
Ok thanks for the info, Could you suggest a good 8x 8x board ?

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Old 24th Nov 2010, 20:44   #10
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http://www.overclockers.co.uk/showpr...=5&subcat=1495

http://www.overclockers.co.uk/showpr...=5&subcat=1495

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Old 24th Nov 2010, 20:50   #11
cmndr_andi
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Originally Posted by Schoieuk View Post
Ok thanks for the info, Could you suggest a good 8x 8x board ?
This one.

i7 3770K @ 4.5GHz//16GB DDR3//Gigabyte Z77X-D3H//MSI GTX 980//Xonar D1//Dell U2412M x2//Samsung 840//HX 850W
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