Radeon 5770 Crossfire causing worse graphics performance

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Peevatab

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Hi there,

I'd really appreciate some help with a problem regarding Crossfire with Radeon HD 5770 cards. First of all I'll give you my system specs.

Sapphire Vapor-X 5770
PowerColor HD5770
8 GB DDR3 RAM
Intel i7 K 875
ASUS P7P55-LX
Xtreme Gear 700 Watt PSU

The problem I've been having is that crossfire appears to be working but I get worse graphics performance than with crossfire disabled. I've observed this in FurMark where I get 46 avg FPS and a score of 2743 with crossfire and 47 avg FPS and a score of 2826 without crossfire. When I run benchmarks in Resident Evil 5 I get an average framerate of 70.1 fps without crossfire and 64.7 fps with crossfire.

I've tried uninstalling all the drivers and installing the latest ones which doesn't seem to solve the problem. Catalyst Control Center says crossfire is enabled and here is what it says about my hardware setup:


Graphics Card Manufacturer Powered by AMD
Graphics Chipset ATI Radeon HD 5700 Series
Device ID 68B8
Vendor 1002

Subsystem ID 1482
Subsystem Vendor ID 174B

Graphics Bus Capability PCI Express 2.0
Maximum Bus Setting PCI Express 2.0 x16

BIOS Version 012.020.000.025
BIOS Part Number 113-E14802-XV6
BIOS Date 2010/07/13

Memory Size 1024 MB
Memory Type GDDR5

Core Clock in MHz 860 MHz
Memory Clock in MHz 1200 MHz
Total Memory Bandwidth in GByte/s 76.8 GByte/s


Linked Adapter
Graphics Card Manufacturer Powered by AMD
Graphics Chipset ATI Radeon HD 5700 Series
Device ID 68B8
Vendor 1002

Subsystem ID 2288
Subsystem Vendor ID 1787

Graphics Bus Capability PCI Express 2.0
Maximum Bus Setting PCI Express 2.0 x4

BIOS Version 012.019.000.003
BIOS Part Number 113-C01301-xxx
BIOS Date 2010/01/28

Memory Size 1024 MB
Memory Type GDDR5

Core Clock in MHz 850 MHz
Memory Clock in MHz 1200 MHz
Total Memory Bandwidth in GByte/s 76.8 GByte/s


Please let me know if you have suggestions of any kind to help me out. Thank you
 
Solution
Yes, that is exactly why. Your mobo is fine. :) The bad part is that it is running in x4 mode. You want at least x8 for GPUs. Although, I would't think you would lose performance with two of them, maybe if you only had one in the x4. I would return your hd5770 and then if you want to CF get a new mobo. Do you have the money for a new one?
You said that it said that CF was enabled but i would turn it off, reboot, turn it on, and then see what happens. One of your cards is lower clocked than the other, when in Crossfire it makes everything drop to lowest common denominator which means that your OCed card will go down to the un-OCed cards performance. Maybe it is just using one card and then lowering the speeds and then not using the other. Other than that, I do not know. I do think that some games do not support multi GPUs, and sometimes in the options you have to turn on multi GPU. In Furmark do you test it in the multi-GPU section?
 

Peevatab

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Although my PSU isn't the best brand, I doubt it's the issue.

I've tried restarting my computer after enabling CF with no difference in FurMark score. I've also tried using FurMark's multi GPU program which shows little difference compared to the normal program. I know Resident Evil 5 supports CF so that's not the problem either.

Not sure what to do from here but I'll put in a picture of my hardware setup although I doubt anything's wrong with it. I know there's been debates over two or one CF bridges but I know newer cards like the 5770 only need one. Also, my Vapor X card came with only one bridge.

IMG_0366.jpg
 

Peevatab

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I think I found the problem. When I put my video card in the second PCI EX x16 slot it gets 10 to 20 fps less in my Res Evil benchmark test compared to when I put it in the first PCI EX x16 slot. Also when my card's in the second slot CCC says "Maximum Bus Setting: PCI Express 2.0 x4" compared to when it's in the first slot and CCC says "Maximum Bus Setting: PCI Express 2.0 x16". Both slots should be x16, not x4. Is this my problem and does it mean my motherboard is defective?
 

Peevatab

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Maybe my mobo isn't defective. Here are the specs that I got from the ASUS website regarding the PCI slots:

1 x PCIe 2.0 x16 (single at x16)
1 x PCI Express 2.0 x16 slot (at x4 mode, 2.5GT/s)
2 x PCI Express 2.0 x1 slots (2.5GT/s)
3 x PCI

Do these specs explain why I see x4 in the second slot? If so, is that what's diminishing performance in that slot?
 
Yes, that is exactly why. Your mobo is fine. :) The bad part is that it is running in x4 mode. You want at least x8 for GPUs. Although, I would't think you would lose performance with two of them, maybe if you only had one in the x4. I would return your hd5770 and then if you want to CF get a new mobo. Do you have the money for a new one?
 
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Peevatab

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Ah ***, figures. I don't want to spend money on a new mobo just so that I can run CF. I'll just return one of my 5770s and go with one for now. Just one is sufficient anyway to handle my gaming needs. Maybe in a couple months I'll upgrade to a better card.
Thanks for your help, HostileDonut.
 
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