16x+16x vs 16x+8x

[Guest]

I just bought an XFX 750i SLI Motherboard, but i just found out that when running on SLI mode one card will run at 16x and the other one at 8x (16x+8x), i also purchased 2 BFG 250 GTS OC 1 GB (each) so i can put them in SLI mode...

I was thinking in returning the motherboard and get a 16x+16x but not sure if it would make a big difference..?

 

[jennyh]

It won't make any noticable difference with those cards.

 

[JackNaylorPE]

It won't make much of a difference w/ the 250's....it starts to matter with the 5870 / 5970 and the GTX 295 and new 400 series.

 

[Guest]

Thank you for your responses, i was kind of hoping to hear that so i don't have to return and get another one etc...

16x+8x doesn't mean the second card will be running at half speed right?

Why does it matter more on the more expensive cards?

 

[paperfox]

The 250 dose not use that much bandwith and loosing half (x16 down to x8) wont bottleneck the cards.

 

[jennyh]

Thank you for your responses, i was kind of hoping to hear that so i don't have to return and get another one etc...

16x+8x doesn't mean the second card will be running at half speed right?

Why does it matter more on the more expensive cards?

Actually, both your cards will be running at 8x8x

But you don't need to worry about it. The 16x pci-e slot was built with future compatability in mind and there is no chance you can hurt performance with a gts250. Even todays top cards run ok at 8x8x so even when the pci-e slots hold the cards back, it's not nearly so bad as half speed - talking 5-10% maximum.

Next gen cards could be a whole different matter though.

 

[AMW1011]

x8/x8 bandwidth will not bottleneck any single GPU, not even the future GTX 4xx series. It will bottleneck dual GPU cards, like the GTX 295 and 5970, but that is it.

 

[Guest]

Great! I won't be returning my XFX 750i Sli mobo then , i was beginning to worry that the second card was going to run at half speed lol, i guess that does not apply at all with the GTS 250...

Thank you for your good responses!

 

[AMW1011]

When you run SLI, both cards will be at x8/x8 speeds or half the bandwidth of x16/x16. This won't effect the performance of any single GPU, even a 5870 or a GTX 4xx.

 

[nanottaja]

Hello!

I have a challenging question for myself but hopefully not for you guys!

My hardware:

Motherboard: Asus P5Q-E

Processor: Intel Core 2 Quad Q8400 @ 2.66 ghz

Graphics card: ATI HD 4890


I would like to update the computers performance with a small budget, and i would like to buy another HD 4890 for crossfire, but the motherboard supports only pci-e 8x in crossfire, so should i update something else or just go for the crossfire?


I found this:

HD 4890 = 975mhz (quad piped - 3.9 GB/s data rate) = 3.9 GB/s total data rate
HD 4870 X2 = 900mhz (quad piped - 3.6 GB/s data rate)(times 2) = 7.2 GB/s total data rate

So as you can see, the 4870 X2 will be hurt in an 8X condition and why the 3870, 4650, 4670, 4770, 4830, 4850, 4870, 4890, and 4850 X2 will not be hurt in performance at all.

From here: http://forums.tweaktown.com/f69/16x-pci-e-vs-8x-pci-e-crossfire-sli-answer-33367/



Do you have any other options? does it make a big difference buying a new cooler for the processor and maybe overclocking it?