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Tom's Hardware > Forum > Motherboards & Memory > Asus > Cant get 2x Asus 4870 to work in Crossfire on ASUS P5KC.

Cant get 2x Asus 4870 to work in Crossfire on ASUS P5KC.

Forum Motherboards & Memory : Asus Cant get 2x Asus 4870 to work in Crossfire on ASUS P5KC.

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Hello, this is my first post here! Hope to find some help.

I have just bought 2x Asus 4870 512mb. I have installed everything as power cables, bridges, etc..

The computer:
2x 4870 512 mb
Asus P5KC
2x 2GB DDR2
intel 2180 cpu
Antec 700w PSU

I began to reformat the computer. Started with the latest Windows 7 64bit. Installed latest Intel drivers, Catalyst 9.12 for win 7 x64 etc.. Installed everything and thought that they would work, but not.

In the catalyst control panel, I can not even activate the crossfire option. In the "graphics hardware" option in the CCC it says "Primary Adapter" and "disabled adapter".

Things I have done:
Updated motherboard bios to latest
Clear CMOS, run with bios defaults
installed win7 installed both 64bit / 32 bit
installed vista 64 bit
reinstalled drivers 2-3 times
tested 9.10 and older drivers
tested with 1 or 2 crossfire bridges
tested each card one at a time, both work well on both single pci-e ports.
cooling is good, with a few extra fans

I've also thought about what I should change the BIOS, there are not many settings that I can relate to Crossfire, I can not, for example manually change the speed of PCIe ports (8x etc). There is a setting called "PEG / PCI" and "PEG plug and play" these i have changed but whithout any results. I there another option in BIOS i should change? Please help me.

here are some print screens from my system
http://img37.imageshack.us/img37/4461/75136681.jpg
http://img121.imageshack.us/img121/4239/74854283.jpg
http://img3.imageshack.us/img3/2427/51941426.jpg
http://img706.imageshack.us/img706/4576/85920040.jpg
http://img130.imageshack.us/img130/7525/74769661.jpg

\\spinxen

Reply to spinxen
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My only suggestion is to check if you've properly connected both cards to your power supply.

------------------------------ Desktop | E7300 | P5KPL-AM | 2GB DDR2 667MHz | NVIDIA 9500 GT | ST3320613AS | w2228h
XPS M1330 | T8300 | Dell 0U8042 | 2GB DDR2 800MHz | NVIDIA 8400M GS | WD2500BEVS-75US | 1280 x 800
Reply to r_manic
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r_manic wrote :

My only suggestion is to check if you've properly connected both cards to your power supply.



Hi, yes both cards are properly connected and they work just fine when i connect a dvi cable to each of them. may the problem be my motherboard? it has support for Crossfire, but not CrossfireX?

Reply to spinxen

i used to have the same problem with my 2 4850's. My problem was that there was not enough power on the rails i was using.. I switched the pci-e power connectors to a different rail and it worked great..

try changing the way you are connecting the power cables (if your antec has more than 1 rail)

also, newegg says the blue slot is at x16 and the black slot is at x4 or x1.. not sure what that means.. might not be enough bandwidth for 4870's..

------------------------------ Intel Core i5 760 | 2x2GB DDR3 Corsair Dominator | Gigabyte P55M-UD2 | XFX Radeon HD 5850 | XFX 650W | OCZ Vertex 2 120GB SSD | Samsung Spinpoint F3 500GB | Silverstone SG-02F
Swiftech Apogee XT | Swiftech QP220 | Laing D5 Vario | XSPC Dual 5.25\" Bay Re
Reply to aberchonbie
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I will try with a new OCZ 700W tomorrow or so, but its weird because they seem to work just fine. thx for the idea!

Reply to spinxen
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