My board only supports Crossfire in 8x/8x as opposed to 16x/16x like the newer boards.

If I were to CF some 4850's or 4870's, would the performance different make the Crossfire not worth the cost of 2 cards?

http://www.tomshardware.com/forum/ [...] sfire-faqs

Dual 8x is a very good configuration too,it doesnt have alot of difference with Dual 16x and its cheaper too.
Chipests like Nvidia 750i SLI, Nvidia 650i SLI,NVIDIA 570i SLI, NVIDIA nForce4 SLI, ATI Radeon Xpress 200, Intel 975x and ONLY 2 Intel P35 boards(ASUS BLITZ FORMULA and ASUS BLITZ EXTREME) support Multi-GPU at dual 8x mode.

It depends on which cards you till run in the 8x/8x configuration.... any of the brand new cards will be bottlenecked and you will not see all the performance the cards have to offer... I know they did testing on the new 4850 and found it was bottlenecked. I can't find the article ATM but Im sure you can search for it.

My advice is unless you are going to use some slightly older cards just put the money into one big monster. This way you will never have to worry about scaling issues some games have with crossfire.

If you were going to crossfire a pair of 3870s I would say go for it because i had a very small performance increase going from 8x8 to an X38 mobo with 2 Pci-e 2 slots. But if i noticed an increase and even a 4850 is more then twice as fast as a 3870 then you would have a serious bottleneck.

P45 supports 8/8 Crossfire also. I have this board, and before I sold my two 4850's for a 4870 I was running them in Crossfire obviously. My GPU scores were about the same as the benchmarks from these review sites using 16/16, I was only around 300-600 points lower which is negligable. The difference between 8/8 and 16/16 is vastly overrated, its by far no monumental gap. The only difference youll see is in 3dmark, youll be kicking the **** out of games regardless.

However if you are going to Crossfire say 4870X2's then youre gonna want to have that X38/X48 board. If youre aiming for the sky, dont shoot at the horizon.

What was the reason for switching 4850 CF for one 4870 ? Planning to CF 4870 in the future or problems with the 4850 CF ?

Any 8x 8x will be fine on any *4* board as they use pci-e2 which doubles the bandwidth for each lane

So they are theoretically equal to 16x 16x pci-e1.



All depends on your motherboard.

are u using a P45 chipset?

Ya, Asus P5Q Deluxe

Don't even worry about it, that's a pretty good set-up and at the 8x/8x bandwidth of PCI-E 2.0 your not really going to experience much bottlenecking, except if your primary game is FSX, otehr than that enjoy.

My graphics upgrade (from an 8800GT) was designed around Age of Conan, its the only game im playing and will be playing for awhile, 8800GT cant max it out with decent FPS. Well AFTER I bought the 4850's I realized Crossfire/SLi just dont work in AoC. Same FPS with 1 or 2 cards. So it was worthless.

Simply put, no. Crossfire takes more bandwidth, due to the way it coordinate the cards. For 4850/70, it'll bottleneck.
http://www.tweaktown.com/articles/ [...] index.html