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I don't think CrossFireX is working?

Last response: in Graphics & Displays
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August 9, 2011 6:07:02 PM

Hi, I recently got 2 1GB Radeon HD 6870's and I can't where to enable CrossFireX in the Cataylst control center. So I checked my system specs and I only have 700MB of GDDR5 memory! I think I was supposed to have 2GB?! Also when I run Bad Company 2 on maxed graphics 1080P I get LOTS of lag. PLEASE HELP!!!! :cry: 

More about : crossfirex working

August 10, 2011 12:36:27 AM

heroicevil said:
Hi, I recently got 2 1GB Radeon HD 6870's and I can't where to enable CrossFireX in the Cataylst control center. So I checked my system specs and I only have 700MB of GDDR5 memory! I think I was supposed to have 2GB?! Also when I run Bad Company 2 on maxed graphics 1080P I get LOTS of lag. PLEASE HELP!!!! :cry: 


First off, when you crossfire two cards, it doesn't double the memory of them, it's still 1gb, also if 1 card has 512mb and the other card has 1gb, then the second card would underclock its memory to 512mb
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August 10, 2011 12:43:16 AM

whatsup1396 said:
First off, when you crossfire two cards, it doesn't double the memory of them, it's still 1gb, also if 1 card has 512mb and the other card has 1gb, then the second card would underclock its memory to 512mb


That's not quite true. Each card uses the memory available to their respective cards. If one card has more than the other, they just use what they have. The problem is that if 512mb will cause a game to slow down, the frames the card with 512mb generates will slow everything down, and it'll run faster when the other card creates it's frame. I imagine this could cause a jittery experience if the difference is big enough.


To the OP:
Where did you read the system spec's from? I've seen Dxdiag report incorrect results with at least some of the 6000 cards. Maybe all of them.
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August 10, 2011 1:00:56 AM

Bad Company 2 uses nowhere close to 700mb at 1080p (not that you actually have 700mb since no 6870s were ever made with less that 1gb) so that is not your issue.

That game is not demanding at all you should be getting like 80 fps or something, what are the rest of your system specs?
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August 10, 2011 3:01:07 PM

Okay my specs:
CPU: i5 2500k 3.3GHz
RAM: Patriot Viper 8 GB 1600MHz
Video cards: 2 XFX Radeon HD 6870
Hard Drive: Seagate Barracuda 1TB 7200RPM
Motherboard: ASUS P8P67 REV 3.0
Case: HAF 922
Power Supply: Thermaltake tough power 775W
Cooler: Cooler Master Hyper 212

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August 10, 2011 3:12:57 PM

Yeah you should have no problems with that game at 1080p even if only a single card is working. I would try reinstalling drivers or maybe a different driver version.

Can you describe what kind of "lag" you are getting in more detail?
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August 10, 2011 6:13:36 PM

bystander said:
That's not quite true. Each card uses the memory available to their respective cards. If one card has more than the other, they just use what they have. The problem is that if 512mb will cause a game to slow down, the frames the card with 512mb generates will slow everything down, and it'll run faster when the other card creates it's frame. I imagine this could cause a jittery experience if the difference is big enough.


To the OP:
Where did you read the system spec's from? I've seen Dxdiag report incorrect results with at least some of the 6000 cards. Maybe all of them.


I don't see how that would work with either SFR or AFR, as you would either have one half of the screen looking better than the other or be flicking between a frame rendered with 512MB of textures say and then one rendered using 1GB of textures. Or do ATi cards do something radically different?
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August 10, 2011 7:23:52 PM

Mousemonkey said:
I don't see how that would work with either SFR or AFR, as you would either have one half of the screen looking better than the other or be flicking between a frame rendered with 512MB of textures say and then one rendered using 1GB of textures. Or do ATi cards do something radically different?


In the case AFR, each card uses its own memory to generate its frame. They operate, at least in the case of crossfire, at what ever frequency you have them set at. Each frame is independently rendered on alternating cards, as a result, the two cards do not have to be equal. If you've ever ran two cards with very different clocks, for example, MSI afterburner will track each card independently at different clocks. They do not sync up. However, the slower card can bottleneck the system.
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August 10, 2011 7:30:23 PM

bystander said:
In the case AFR, each card uses its own memory to generate its frame. They operate, at least in the case of crossfire, at what ever frequency you have them set at. Each frame is independently rendered on alternating cards, as a result, the two cards do not have to be equal. If you've ever ran two cards with very different clocks, for example, MSI afterburner will track each card independently at different clocks. They do not sync up. However, the slower card can bottleneck the system.

When I last ran cards of different speeds MSI Afterburner did not exist. :whistle: 
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August 11, 2011 5:49:06 PM

benski said:
Yeah you should have no problems with that game at 1080p even if only a single card is working. I would try reinstalling drivers or maybe a different driver version.

Can you describe what kind of "lag" you are getting in more detail?

Like skipped frames once every few seconds
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