Cant get my PCI-E Slots to run 16x/8x

100Core

Member
Mar 8, 2009
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I recently purchased a 4850 to crossfire with my 4870 but am having some trouble.

The UD3P supports 2 VCards, one at 16x, and one at 8x, but I cant seem to get this running.
With just one card in slot 0, it runs at 16x just fine, but when I through the other one in slot 1, both run at only 8x according to CCC.

Cant seem to find anything in CCC or the bios. Anyone know how to fix this?
 

Tempered81

Diamond Member
Jan 29, 2007
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try swapping the cards:

You know you're only going to get 4850 crossfire performance from 4870 + 4850.
 

yh125d

Diamond Member
Dec 23, 2006
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Yep. 16 pci-e lanes total. Don't worry though, your setup won't be saturating an 8x bus
 

apoppin

Lifer
Mar 9, 2000
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alienbabeltech.com
Originally posted by: jaredpace
try swapping the cards:

You know you're only going to get 4850 crossfire performance from 4870 + 4850.

no he is not
he will get better than 4850 CF performance in Crossfire-X with his frankenfire :p

p45 is generally 8x+8x PCIe CF lanes when used together - not an issue for 4870 class
 

Nathelion

Senior member
Jan 30, 2006
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The 8x bus won't be a real issue. And yeah, the 4870 will give him a little bit of a boost, but not much.
 

100Core

Member
Mar 8, 2009
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thx all

Ya the difference in performance is almost negligable, but it is definately there. I mostly play crysis and l4d, both at 1900x1200 with maxed out settings except for AA in Crysis. I did get a few fps better for both games, but still cannot handle AA in crysis (probably because both cards are 512mb ram).

Question: When two cards are crossfired, is the ram between them combined or just the processing power? From what I can tell, my two 512 cards are not acting like a 1gig card (cant really even handle 2x AA in Crysis).

In any case, Im a bit dissapointed with what crossfire has to offer, I was hoping for a 20-40 percent increase in performance from adding a 4850 to a 4870. Its more like 10 percent! thats pretty week for a whole entire card being added... but hey, at least I have more monitor connections right?
 

apoppin

Lifer
Mar 9, 2000
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alienbabeltech.com
Originally posted by: 100Core
thx all

Ya the difference in performance is almost negligable, but it is definately there. I mostly play crysis and l4d, both at 1900x1200 with maxed out settings except for AA in Crysis. I did get a few fps better for both games, but still cannot handle AA in crysis (probably because both cards are 512mb ram).

Question: When two cards are crossfired, is the ram between them combined or just the processing power? From what I can tell, my two 512 cards are not acting like a 1gig card (cant really even handle 2x AA in Crysis).

In any case, Im a bit dissapointed with what crossfire has to offer, I was hoping for a 20-40 percent increase in performance from adding a 4850 to a 4870. Its more like 10 percent! thats pretty week for a whole entire card being added... but hey, at least I have more monitor connections right?

First of all, Crysis does scale pretty well and does not have any issues with 512 MB vRAM at 19x12 generally
-the RAM is not combined - but does not make more than 1 FPS difference with a 1GB 4870 vs a 512MB version

my 4870 gets 17.35 average FPS at 19x12 all very high plus 4xAA/16xAF
4870-x2 gets 29.33 average FPS at 19x12 all very high plus 4xAA/16xAF

are you sure CrossFire-X is enabled?
- look in CCC diagnostics to be sure
rose.gif


a 4870+4850 is still pretty fast and a bit faster than 4850 CrossFire