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Differences between SLI x16 and x8

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December 11, 2007 8:34:53 AM

I am currently in a situation in which i need to decide if im going for a motherboard which supports SLI x8 x8, or x16 x16. Money is not an issue in the decision. Only performance.

My question is, how big of a difference (decrease in performance) is it to run 8800GT in SLI on x8 x8, like on an Asus P5N-E SLI motherboard, with nForce 650i chipset, as opposed to a SLI x16 x16 on an Asus P5N32-E SLI motherboard, with nForce 680i?

More about : differences sli x16

December 11, 2007 9:36:08 AM

The P5N32-E SLI is the better board.
December 11, 2007 10:35:49 AM

Can you evaluate the performance difference between the 2 in running SLI?
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December 11, 2007 10:38:11 AM

Better check your info, Im 99% positive the plus version (650i) is 16X on both slots. Not to mention everyones "sweet" 680i boards cant use the new intel chips (45nm) hahaha, they got tricked. You decide, I have the plus version and Im very happy with its performance. Infact, I have had some of my freinds with some of the other boards(p35, 680i), and their upset of the overclocking ability, the plus version has many incraments (spelled wrong) and variability to its features. Good luck.
December 11, 2007 11:29:13 AM

I thought 650i were 8x lanes and the 680i was the beefy version of it?
December 11, 2007 12:51:20 PM

There are two motherboards using the 650i chipset.

One of them is the smaller, older one named P5N-E SLI. It uses x16 slot for Single VGA, and Dual x8 for SLI.

The other one is a 650i in disguise of a 680i mobo. The P5N32-E SLI Plus is a newer version of the 680i mobo but it actually uses a 650i NB. It works with Dual x16.
December 11, 2007 1:13:59 PM

Well their ya go, answered your own question lol
December 12, 2007 5:24:49 AM

No, i didn't. My question was about the difference in performance between the 2...

But Maziar already answered for me, thanks.
a c 169 U Graphics card
a c 135 V Motherboard
December 12, 2007 10:28:21 AM

No problem mate :)  glad i could help u
December 12, 2007 12:12:55 PM

You will see some performance loss with the 8x by 8x.
The newer top end cards slightly push the 8x bus, but not drastically.

The 680i/780i may not support the 4core 45nm chips.
The dual core are supported.
a c 169 U Graphics card
a c 135 V Motherboard
December 12, 2007 12:13:28 PM

P5N-E SLI , P5N32-E SLI, P5N32-E SLI PLUS, STRIKER EXTREME, STRIKER all support next gen 45nm CPUs:
http://event.asus.com/mb/45nm/

P.S: even in the link u posted, it says they support next gen 45nm CPUs
December 12, 2007 12:14:24 PM

I read the link posted by Maziar (very interesting!)
But the review of the board featured is a couple of years old.
I just wanted to query something that I am considering.
I've just ordered a replacement board for my AM2 system which is SLi compatible (570 SLi chipset) and just wondered whether it would bottleneck SLi'd GTX's on it?
I currently have an XFX GTX but would buy another as I'm sure prices are going to drop as the G92 GTS is such a stron performer!
Basically, is x8 SLi (which I believe is what the 570 chipset is capable of) going to bottleneck GTX's, and if so, to a point that there would be little benefit?
Thanks! :) 
a c 169 U Graphics card
a c 135 V Motherboard
December 12, 2007 4:05:41 PM

That link that Paul posted is very useful, definitely check it
December 12, 2007 6:42:12 PM

Thanks very much :) 
That link was really useful!
Basically, I'd have been a mug to go for the (significantly) more expensive 590 SLi chipset! The 570 has everything I need, so it really would have been a waste of £50 (approx $100) for the 590.
That £50 will go nicely towards another GTX :) 
I'm surprised the difference was as much as 2/3 fps! Just shows x8 bandwidth is still plenty for modern cards!

Thanks
a b U Graphics card
December 12, 2007 9:09:18 PM

That link had convinced me to go with a 650i based mobo instead of the 680i with plans of 8800GT SLI. $70 savings was worth it to me.
a c 169 U Graphics card
a c 135 V Motherboard
December 13, 2007 8:07:49 AM

Agreed^^
March 13, 2011 10:44:07 PM

I have a very similary question.
I will have to by a
Gigabyte GA-P67A-UD4 Socket 1155 USB3 og S-ATA3
to use SLI, but will there be any difference in the SLI changing both express x to 8, when the two pcex are in use?
Reason for buying this mobo is that seller only has this which can be used with SLI and the i5-2500 cpu.

I am not hardcore power gamer, for futher ref read my first question thread
http://www.tomshardware.co.uk/forum/311679-15-final-cho...
March 14, 2011 12:25:12 AM

Going X8/X8 or 16x/16x won't make a difference. Both X8 and x16 bandwidth is theoretical so it can never be achieved. Have no clue why they do benchmarks on different systems because the small difference are thanks to the triple channel ram of the x58. Intels PCI-E whitepaper stated using 3 way in 8x mode the overhead and latency drops the third device down to 70 percent performance. All the board manufacturers did was they added a chip which reduced the latency and overhead
March 14, 2011 12:30:23 AM

I have at the back of my mind that dual X16 is better for Quad SLi. With dual 8800s it won't matter.
a b U Graphics card
a b V Motherboard
March 14, 2011 2:46:28 AM

with them cards theres no impact running at x8 mode as they don't really require a huge amount of bandwidth
now if you were running sli gtx570's then you really will need x16 lanes per card.

!