X38 or P35 chipset for a crossfire configuration?

[fasteddie042]

Hello!

I am hoping that someone will be able to answer this one for me, I am the proud owner of 2 HD2900xt's and am going to be running them in crossfire in the very near future. In order to get the new system up and running a new motherboard is in order and I am stuck between boards with the X38 chipset or the P35 chipset. I know that the X38 can run both PCIe slots at full x16 but will the 2900's take full advantage of this? Can the 2900's use the full x16 in crossfire? can they use it when they are not in crossfire? or does the P35 configuration of x16 and x4 max out the cards full ability? I have spent a few night looking and alas have not found the answer.

anyone know?

 

[blackened144]

The 4x slot will severely limit the potential of the second card. For Crossfire, you would be better off going for the X38.

 

[Maziar]

Hello and welcome to the forums mate

well all P35 boards CrossFire mode is limited to 16x4x except for ASUS BLITZ FORMULA and BLITZ EXTREME, which are dual 8x

so i recommend u getting X38

 

[fasteddie042]

I should probably also add that I am not going to be doing any serious upgrades once this system is built. So once the mobo/cpu and videocards are in it I am going to leave it at that. Is there any others that I should be looking at?

 

[mattman5170]

Currently I don't think any graphics cards on the market currently max out the PCIe x16 bandwidth.

I cant remember which tech site did a write up on this, but I remember reading somewhere that there was not much of a performance difference between two cards running SLI/Crossfire with a dual x8 board and a dual x16 board. I think the difference was less than 10% between the two if I remember correctly. But this articale was written a year or more ago so... the cards out today are alot faster.

IMO the X38 is a more future proof board but it is also super expensive.

With SLI/Crossfire, I think that one card performs most of the graphics processing like 80%, while the other picks up the other 20% of the processing. I am fairly certain both cards do not evently distibute processing loads where 1 card does 50% of the processing and the other card processes the remaining 50%. So if you need to save money, I don't think you would notice too much of a performance difference between the x38 and p35 chipsets when running a Crossfire configuration.

 

[Maziar]

Dual 8x doesnt have alot of difference with Dual 16x
Dual16x vs Dual8x :
http://www.xbitlabs.com/articles/mainboards/display/asus-a8n32-sli-deluxe.html
(Its old but its a very good app)
but they both have alot of difference with 16x4x

 

[mattman5170]

You may want to consider a mobo that uses the ATI 3200 Express chipset, if money is an issue. That chipset run both PCie slots at x8 which like I said before as well as Maziar isn't really that much different than a true dual x16 setup.

I would definately read the article that Maziar posted, it may give you some info your looking for.

 

[rubix_1011]

I have an ASUS P35 board and it has 2-x16 PCIe slots. Even if the 2nd slot reverts to 8x, I HIGHLY doubt any current system will be hindered by it.