Crossfire

J

JunK

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Mar 17, 2009
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Ok i need some help. Im trying to figure out which is better, price wise, crossfire x8+x8 or crossfire x16+x16. obviously the 2x16 is better, but really by how much?
Im having a lot of difficulty trying to find benchmarks with this anywhere. the ones i find are like from 2006/2007.

pretty much i want to know what motherboard i should get. a 790gx or fx. for example just look at these

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131361&cm_re=790fx-_-13-131-361-_-Product
vs
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131368&cm_re=asus_m4a78-e-_-13-131-368-_-Product

im still torn if i want to get am2+ versions of the 790gx/fx or am3. either way the argument is the same, x8 or x16 for crossfire
I will be getting a single 5850 however late next year or just when the 5000 series drop in price i will think about picking up a second card. So it will not be for awhile that i will think about crossfire, however it will probably happen instead of buying another single GPU in the future.
So can anybody shed some light including benchmarks between the 2 or anything? because i'd prefer not shedding out a lot of extra money now for like 10% difference later
 
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I know a GTX 295 is BARELY bottlenecked on x8(2.0). A 5850 will probably not be bottlenecked at all.

I'd get an AM3 board. No sense investing in old tech.
 
ya i just realized in order to run a 955/965 i'll need a new board anyway, so im going with am3. but im not talking about a x8 pci-e vs x16 pci-e single, but in sli/crossfire. however i assume what you're saying applies to both too.
my local store has THIS board for 120 CND which i think will be great
 
go with x16/x16 trust me you will be happier and more glad you did so..........im pretty mad that i didn't go like X48 or something but then again, when i chose the mobo i didn't really know as much as i know now......stuck with an oldddd P35 now grrrr but atleast i can run a single card at x16

They have benchmarks showing 2x5850 getting bottlenecked in a couple games, i dont think its the Pci-e slot tho, more of the CPU but still it bottlenecked in a couple games like COD and such.

The average performance decrease between x8/x8 and x16/x16 varies between games, some games like crysis show a larger decrease in performance while some games only show decreases in performance of like ~2FPS or something

I personally say x16/x16 especially if your gonna go 2x5850, your gonna want as much performance from 2 of those things as possible and get your moneys worth =)
 
perfrel_1920.gif

A 5870 loses 1-2% on PCIe 2.0 x8(at 1920x1200). To put that into perspective, if it gets 60FPS on x16, then you would get somewhere between 58.8-59.4 on x8. A 5850 will be less or none at all.

It won't really matter. But for the sake of futureproofness, I'd get an x16 x16 board.

@PewPewBangBang, it would not be dependent upon the game. It is a bandwidth issue. It would be dependent on resolution, AA setting, and the cards in said slots. The coding of the game itself is basically irrelevant in this scenario.
 
FreakingHell said:
perfrel_1920.gif

A 5870 loses 1-2% on PCIe 2.0 x8(at 1920x1200). To put that into perspective, if it gets 60FPS on x16, then you would get somewhere between 58.8-59.4 on x8. A 5850 will be less or none at all.

It won't really matter. But for the sake of futureproofness, I'd get an x16 x16 board.

@PewPewBangBang, it would not be dependent upon the game. It is a bandwidth issue. It would be dependent on resolution, AA setting, and the cards in said slots. The coding of the game itself is basically irrelevant in this scenario.
Click to expand...

http://www.tweaktown.com/articles/1472/intel_p45_vs_x48_crossfire_performance/index7.html
okay but still the decrease in performance varies between games......look, some games suffer more than others at one resolution between x8/x8 and x16/x16 while at some games there is barely any difference at all between the 2 at the same resolution.

yes i realize resolution and AA play a factor due to bandwith.

I actually might want to pick up a 5850 myself because my vid card is fried i think, was vacuuming and then when i turned it on, i would get no video...i explained it all in the tech help thread so if any of you guys got ideas, id be willing to listen.

Junk, there are benchmarks of a 5850 beating a 5870 =D, they used MSI afterburner to get overlocks of like 1010 mhz core on a 5850 and it beasted, they said temps never went higher than 70 with fan at 50% or around that, its pretty sick so i might wanna pick up an XFX black edition if i do get a 5850 so i can hopefully get a higher OC over the regular 5850's
 
PewPewBangBang said:
http://www.tweaktown.com/articles/1472/intel_p45_vs_x48_crossfire_performance/index7.html
okay but still the decrease in performance varies between games......look, some games suffer more than others at one resolution between x8/x8 and x16/x16 while at some games there is barely any difference at all between the 2 at the same resolution.

yes i realize resolution and AA play a factor due to bandwith.
Click to expand...

That review is comparing two different chipsets, which brings too many other variables into the equation. The proper way to benchmark this is to use a board with both x8 and x16 slots(such as the EVGA X58 SLI), and bench a card in an x16 slot, and then bench the same card in an x8 slot on the same board.
 
FreakingHell said:
That review is comparing two different chipsets, which brings too many other variables into the equation. The proper way to benchmark this is to use a board with both x8 and x16 slots(such as the EVGA X58 SLI), and bench a card in an x16 slot, and then bench the same card in an x8 slot on the same board.
Click to expand...

Okay, figured the chipset didn't matter much because only X48 are capable of doing x16/x16 just like only x58 can do x16/x16 and p45/p55 can only do x8/x8 so it was only a battle between x8/x8 and x16/x16
 
I say x8. The minor performance difference is not worth $70 US. The M4A79XTD EVO looks like a good deal, I think you would be more than happy with it.
 
PewPewBangBang said:
Okay, figured the chipset didn't matter much because only X48 are capable of doing x16/x16 just like only x58 can do x16/x16 and p45/p55 can only do x8/x8 so it was only a battle between x8/x8 and x16/x16
Click to expand...

Yeah, even though there isn't much different spec wise other than PCIe lanes, there are a lot of differences. The lower end chipsets would be a lot more expensive if the only difference was the number of PCIe lanes.
 
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