Question about Crossfire with 16x and 4x slots....

[GuitarrassDeAmor]

If I wanted to get another 3870, which I was thinking about doing....

How would it perform? One of my slots is at 16x, and one is at 4x. My card is in the 16x obviously now, but how would it perform at 4x with another card?

[Reagan1981]

idk, im thinking both will run at 4x if they goto crossfire mode. PCI 4x is definitely going to cut the performance down by a good chunk. Let me try to find the article on the same cards on different bus speeds.

[Reagan1981]

http://www.tomshardware.com/2008/01/23/crossfire_meets_pci_express/page4.html

Here's the link to crossfire in 16x and 8x. Its very obvious, you gain about 15% fps from both being in 16x.

And luckly i got a sli 16x 2.0

Because even 16x 1.0a compared to 16x 2.0 pcie the 2.0 version gains about 3-5%.

SO in the future, ill have the ability to upgrade with more power.

[GuitarrassDeAmor]

What....? I just need about 4x and stuff....I didn't really read the article (don't have time) but I am talking about my board bro...if you wanna get posts up do it in general discussion.

[RedSand426]

What....? I just need about 4x and stuff....I didn't really read the article (don't have time) but I am talking about my board bro...if you wanna get posts up do it in general discussion.
Hey don't take it out on him.. it's not his fault you bought a crappy motherboard :p

http://img152.imageshack.us/img152/8240/cod2gl8.jpg
http://img150.imageshack.us/img150/557/fearcg7.jpg
http://img136.imageshack.us/img136/1387/quakerf4.jpg
http://img233.imageshack.us/img233/7264/supremecommandernh0.jpg
http://img205.imageshack.us/img205/5515/wocrj7.jpg


<H2>Conclusions

I'm genuinely surprised, that the extra bandwidth actually does make a difference in some areas, but it didn't surprise us that there were cases where it didn't make any difference. Obviously we have the latency difference between motherboards and marginal extra performance the X38 brings, to take into account too, but the general consensus is you will likely see some improvement the more bandwidth you throw at CrossFire.

However the actual degree of performance increase depends on how much your graphics cards of choice use the bus when operating in a multi-GPU configuration. If your cards are working harder doing more internal calculations, like for anti-aliasing or anisotropic filtering for example, there will be less data being sent between them as fewer frames are being rendered.

This is all a bit irrelevant though, as performance differences were quite often so small that general system optimisation or gentle overclocking of either the CPU, front side bus or graphics cards will negate any performance difference. That's not including just simply overclocking the PCI-Express bus to give you more speed if you're width is restricted to x8 or x4.

We would recommend avoiding virtually every P35 board that sports CrossFire as a feature, but that's not to say you should avoid P35 boards as a whole though - it's just CrossFire on in this situation is financially stupid. Why pay for a cheaper P35 board and then fork out for two expensive graphics cards when you can't get the most out of them?

We've always maintained that any multi-GPU system should only be considered if you've already run out of headroom after buying the fastest card anyway, so you're already financially committed. Don't go for a cheap rig with two mainstream cards and a mainstream board - it's still not worth it. A faster single card will not only offer better game compatibility, but more motherboard choice, generally lower power consumption and might also work out cheaper too.
</H2>http://www.bit-tech.net/hardware/2007/10/12/crossfire_comparison_intel_x38_versus_p35/8

[Reagan1981]

Hey don't take it out on him.. it's not his fault you bought a crappy motherboard :p


heh Quoted for the truth ;)

[GuitarrassDeAmor]

If you pass up a motherboard with 2 PCI-E slots that is still $134 on Newegg coupled with a processor that is $234, FOR ONLY $200, you are an idiot.

[GuitarrassDeAmor]

If I sounded like a **** earlier, please forgive me.

I am happier now, this Vista SP1 better make me even freaking happier!!!!