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View Full Version : HELP: Crossfire refuses to turn on!

Oversized Rooster
Feb 24th, 2008, 02:30 PM
Guys I'm hoping to receive some advise on a Crossfire setup. Basically, Crossfire refuses to power up!

First off, here are the system specs:

Core 2 Duo E6850 running at 3.8GHz and 1688FSB
Asus P5K Premium WiFi P35 Mobo
2 x 2GB Mushkin DDR2-800 RAM
74GB WD Raptor HD
3 x 500GB WD HDs
PCP&C Silencer 750W PSU

Vista Business 64-bit
Catalyst 8.2 video card drivers

512MB Radeon HD 3870 PCI-E by Sapphire
512MB Radeon HD 3870 PCI-E by PowerColor

2 x Dell 19" LCDs (on each side)
22" LG LCD (in the center)

They are both running at 850 core and 1200 memory. Each has a dual slot cooler and nothing is overheating.

So the problem is that in Windows, I can set CrossFire to on. Then my primary screen only is on (the center 22-incher). However, CrossFire actually does NOT turn on. 3DMark still sees a single card (and my score reflects this). GPU-Z also shows CF as still being disabled.

On the hardware side, I have dual Crossfire bridge cables attached.

I've flashed my mobo to 0504 BIOS which is the newest.

I've tried doing a fresh install of the Catalyst 8.2 but no luck.

What can I do to make Crossfire actually turn on?
board123
Feb 24th, 2008, 02:58 PM
Try it with one Crossfire bridge. All of the HD 3000 series cards are supposed to run with just one bridge.

Regardless, Crossfire performance on your system is going to suck because you're using a P35 motherboard...
Oversized Rooster
Feb 24th, 2008, 03:31 PM
Try it with one Crossfire bridge. All of the HD 3000 series cards are supposed to run with just one bridge.

Regardless, Crossfire performance on your system is going to suck because you're using a P35 motherboard...

1) Does it matter which of the two bridges I remove?
2) Why is a P35 mobo a bad platform for this?
board123
Feb 24th, 2008, 03:41 PM
1) I'm pretty sure it doesn't matter which of the two connectors you use. Try both.

2) P35 only supports Crossfire on 16x/4x lane configuration. Your second card won't scale properly.
nite4evr
Feb 24th, 2008, 03:46 PM
1) I don't think it matters either

2) Because you're using a Intel chipset instead of a AMD chipset.
board123
Feb 24th, 2008, 04:12 PM
2) Because you're using a Intel chipset instead of a AMD chipset.
Wrong...
Oversized Rooster
Feb 24th, 2008, 04:51 PM
Alright I solved the problem.

Using a single bridge cable instead of 2 didn't change anything.

However, my problem was caused by driver settings.

Specifically, I was running 3DMark06 with AA at 8X and AF at 16X. Therefore, my 3DMark score was higher by 500-1000 points while rendering much higher quality stuff.

When I put the AA and AF to application preferance, I could finally compare to my previous score which was done this way.

I'm now at 17621 points up from around 12000. All software continues to "say" that CF is off, however it's actually on and I can SEE the difference.

I could never before run Flight Simulator X at 1650x1050 at nearly max settings with 8X AA and 16X AF. Now I can! :)