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would my cpu bottleneck crossfire ?

I bought my Powercolor HD4850 from Ebuyer.com for £117!! with free postage...getting another soon.
 
Yup great price. I was tossing the idea up of getting a 4850, but now I have 2 3870s that arent bottlenecked.. they pull about the same as a 4850 CF setup, so not much point :p
 
yep... madness ... you should see what the GX280's cost :P
 
well only one persion is happy with the price's , any one care to take a guess who that is ? lol












small clue (v.a.t) :p
 
Bottleneck.

That's the only of the reason i got only one 4870. Put 2 of these would just waste money as i don't go above 1680X1050.
 
I'm having a similar issue. My PC had just the X2 4000+ at 3Ghz and a Radeon 3850 256mb. Clocked at 750/1000, I received about 9400 on 3Dmark06 @ 1440x900 (very close to 1280x1024 default).

Today, I added in Radeon 3870 gDDR4 at default speeds to the mix. I tried uninstalling the drivers with the 3850, putting the 3870 in slot 1 and 3850 in slot 2, installed 2 crossfire bridges, then Catalyst 8.7 + CCC, and then enabled CrossfireX. My score went up by only about a 1000 points (I was expecting quite a bit more). Then I tried Crysis. Not really much of an improvement at all over the 3850.

Then, I saw the sticky in this forum about how to setup CrossfireX and I followed that to the letter. It was no better than when I first did it. Crysis performance wasn't any better either. Obviously both cards are running with 256mb RAM (uses the lowest of the two), but at 1440x900, that should be fine, correct?

Was I wrong in hoping that I would be able to run Crysis on high at 1440x900 smoothly with a 3850/3870 CrossfireX setup without AA? Perhaps I'm CPU bottlenecked?

Edit: added a picture that shows that while I'm in CrossfireX, CCC says that my 3850 is disabled. And no, that doesn't fix itself if I close CCC and reopen it.
 

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devguy said:
I'm having a similar issue. My PC had just the X2 4000+ at 3Ghz and a Radeon 3850 256mb. Clocked at 750/1000, I received about 9400 on 3Dmark06 @ 1440x900 (very close to 1280x1024 default).

Today, I added in Radeon 3870 gDDR4 at default speeds to the mix. I tried uninstalling the drivers with the 3850, putting the 3870 in slot 1 and 3850 in slot 2, installed 2 crossfire bridges, then Catalyst 8.7 + CCC, and then enabled CrossfireX. My score went up by only about a 1000 points (I was expecting quite a bit more). Then I tried Crysis. Not really much of an improvement at all over the 3850.

Then, I saw the sticky in this forum about how to setup CrossfireX and I followed that to the letter. It was no better than when I first did it. Crysis performance wasn't any better either. Obviously both cards are running with 256mb RAM (uses the lowest of the two), but at 1440x900, that should be fine, correct?

Was I wrong in hoping that I would be able to run Crysis on high at 1440x900 smoothly with a 3850/3870 CrossfireX setup without AA? Perhaps I'm CPU bottlenecked?

Edit: added a picture that shows that while I'm in CrossfireX, CCC says that my 3850 is disabled. And no, that doesn't fix itself if I close CCC and reopen it.
Click to expand...


cpu bottlenecks 3dmarks which aren't really that important and crysus doesn't do too well with crossfire. try another game and you'll se an improvement. but really for crysis, you need an nvidia card.
 
Still, looking around at other 3850 and 3870 crossfire 3dMark runs, my SM2.0 and SM3.0 scores seem around the performance of a single 3870. Here's what a run looks like:
 

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