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Bottle necking

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December 17, 2009 9:43:30 PM

Hi,i was wondering,i have 2 4870`S running in crossfire and i have got to be honest i thought that they would perform better than they do,sometimes i get better performance running just the one card. My question is, i have a AMD X4 9950 2.6ghz Black Edition processor,could this be bottle necking and reducing the performance of the cards.I was thinking of getting a single 5870,but if the processor is not up to it then there is no point.I am running windows 7 with 8Gig of ram. Also i will be building a pc for my bro this weekend,would the AMD Phenom II X4 Quad Core 955 Black Edition 3.20GHz (Socket AM3) be a good processor to use with a ATI 5870 GPU.Any help would be greatly appriciated.

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December 17, 2009 9:49:26 PM

i have the 955, and i cant say enough good things about it. but, i think that a quad core that is decent would have a hard time bottle necking those two cards, but it might be bning them a little. the 955 would be a perfect match for the 5870, and 1 5870 probably is close to equivalent to 2 4870. i would highly recommend buying the 955, as it is only 165$.
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December 17, 2009 9:55:31 PM

I'll take one of those off your hands if you don't need them both! Well, I'd pretty much only want a Vapor-X model, though, and they're sold out basically everywhere!


The CPU might be bottlenecking, depending on your resolution. Can you overclock your CPU a bit? If so, try it at like 3GHz and see if your frame rates go up.
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December 17, 2009 10:11:34 PM

Yeah try OCing your CPU but if you ask me you'll want a Phenom II to keep up with 4870 crossfire. Just know you won't see much of an increase in performance, if at all, using a 5870 compared to 2 4870s. With the exception of games that are only optimized for a single GPU of course, but those games should be more than playable on even a single 4870.
December 18, 2009 5:42:14 PM

Thanks for the replies guys,sorry i forgot to mention that my processor is a Phenom II,my motherboard supports AM2+,i know that the phenom 955 is AM3 but does support AM2+,but iam thinking that i would not really see any performance gains as i would not be running it to its potential.Iam ok at building pc`s but i have to say that iam a comlete noob(or nob lol) when it comes to overclocking anything. I only built my pc about 8 months ago so i dont want to throw to much more money at it. Im playing Dirt 2 at the moment and that seems to run better with the one card apposed to crossfire,thats why i was thinking of going to a single 5870,as ares1214 mentioned one of those is more or less equivalent to two 4870,but as i said if the processor it not quite up to the potential of the cards i may as well keep what i have,plus they are only directx 10.1,games are now coming out in direct 11,holy its hard to keep up lol.Thanks again for taking the time to reply.
December 18, 2009 5:49:44 PM

Oh i forgot to mention my resolution is 1920x1200,dont know if that makes any difference.
December 18, 2009 6:12:07 PM

Depending on a few things here.
1 is, at 512mb on your cards, the 19x12 will have a big effect, and 2 is, yes, look here
http://www.legionhardware.com/document.php?id=869
Anything under 3Ghz with a Phenom is causing slow downs, and a 5870 wont give you the ooomph youll want, unless you get those cpu clocks up
IMO this also plays to the 4870s as well, as theyd indeed see some nice improvements with higher clocks
December 18, 2009 7:47:04 PM

Do you mean 512mb on my cards?,if so no they are 1 gb each,and thankyou for the link and the reply,looks like i have got to step into the worl of overclocking lol
December 18, 2009 11:58:13 PM

Yea, with those 1 Gig cards youll be fine, just bump those clocks
December 19, 2009 12:12:58 AM

Well i have clocked my cpu to 2.9 ghz and put the latest drivers on my card and holy fook,it was as glichy as hell,but as soon as i dropped it to a single card again it was fine,maybe Dirt 2 does not like crossfire.They say that in crossfire you only gain about 30% performance,so if i was to get a single 5870 would that not improve my performance?.The reason i say that is that two 4780 are more or less the same as a a single 5870 but in crossfire i am only gaining another 30% but if i had a single card with the power of two would i not get better performance because its not two cards relying upon a bridge to link the two card together?
December 19, 2009 12:18:06 AM

I think after the drivers have matured on the 5870, youll see it as fast or slightly faster than your setup in CF.
Plus anything DX11 will be faster as well.
Its close already
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December 19, 2009 12:18:25 AM

could be the power supply.
December 19, 2009 12:21:08 AM

Yea, the psu could be bad.
Id check your CF profiles as well, and maybe try new drivers one more time.
December 19, 2009 6:41:00 AM

Ok,thanks for all the feed back,i very much appriciate it,but without sounding like to much of a noob lol,what do you mean by checking my CF profiles?i just use the ccc to see if its on or not,but at the moment iam not running CF as Dirt 2 does not seem to like it,and is there anyway of testing the PSU,or is it a case of trying another on?
December 19, 2009 1:50:33 PM

What kind of psu do you have, and does this happen only when using 2 cards?
If its underpowered, it could cause various issues
December 19, 2009 3:10:35 PM

Its a OCZ 1000 watt psu,its only about 6 or 8 months old,well all of my rig is,i built it with all new parts
December 19, 2009 3:58:54 PM

Then its most likely not your psu, and it could be simple driver conflicts. Make sure you have your CF set right, and if problems still occur, switch cards for single card usage, to see if 1 card is bad vs the other, or if its drivers, try new driver downloads, the 9.12s are out with a hotfix as well, and redownload them
December 21, 2009 9:14:01 PM

Done that and it appears to have done the trick,i ran the benchmark test that in the game of Dirt 2 and got a avarage of 74fps,so i am well happy with that,just getting some screen tearing now so ill try vsync. Thanks so much for your help.
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