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Old 04-02-08, 10:20 PM Thread Starter   #1
Neuromancer
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Crossfire 16x/4x


Since ATI released the 3850 on AGP 8x and is releasing the 3870 on AGP...

There should be no problem with crossfiring 2 3850s on a 16x/4x PCIE motherboard right?

Would using two bridges instead of one prevent any problem if there is on?

I thought that it was a bottleneck, but seeing these agp cards has me thinking a second 3850 512MB might be in my future...
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Old 04-04-08, 12:24 PM   #2
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Very good question. I was about to start a new thread when I saw this one. Maybe we can both get help at the same time.

I also have a 16x/4x, ASUS Commando, board and recently just bought a 2nd 2900XT and couldn't quite get it working 100%.

This is the first time I've crossfired and found that my 2nd card ( Sapphire 2900XT ) was running only on 2D clocks ( 510/519 ) and the first was running stock ( Diamond 2900XT 825/1075 ). I was using both bridges and ATItool .27 Beta4. I tried Riva and got the same results, but was able to get both fans at 100% duty.

BUT, are you talking about using AGP or PCI-E? Sorry if I misunderstood your thread.

I would like to know what the best way to Crossfire 2 2900XT 1gb's is.

PS: Crossfire bridges are WAY TOO fragile. I am waiting on a new set because I tried to take them off to get to my CMOS reset switch and the ribbon cable pulled away from the clips VERY easily rendering them completely useless. I wasn't even trying to force them either. Wow was I mad.....

Last edited by Sarsbaby; 04-04-08 at 12:24 PM. Reason: forgot something.
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Old 04-04-08, 12:31 PM   #3
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Quote:
Originally Posted by Sarsbaby View Post
Very good question. I was about to start a new thread when I saw this one. Maybe we can both get help at the same time.

I also have a 16x/4x, ASUS Commando, board and recently just bought a 2nd 2900XT and couldn't quite get it working 100%.

This is the first time I've crossfired and found that my 2nd card ( Sapphire 2900XT ) was running only on 2D clocks ( 510/519 ) and the first was running stock ( Diamond 2900XT 825/1075 ). I was using both bridges and ATItool .27 Beta4. I tried Riva and got the same results, but was able to get both fans at 100% duty.

BUT, are you talking about using AGP or PCI-E? Sorry if I misunderstood your thread.

I would like to know what the best way to Crossfire 2 2900XT 1gb's is.

PS: Crossfire bridges are WAY TOO fragile. I am waiting on a new set because I tried to take them off to get to my CMOS reset switch and the ribbon cable pulled away from the clips VERY easily rendering them completely useless. I wasn't even trying to force them either. Wow was I mad.....
I'm looking at doing the exact same thing with an Asus Commando, and was wondering what kind of performance hit the cards would take due to one running in 4x mode. Do the CCC show "Crossfire" enabled?

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Old 04-04-08, 02:06 PM   #4
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Originally Posted by ghost_recon88 View Post
I'm looking at doing the exact same thing with an Asus Commando, and was wondering what kind of performance hit the cards would take due to one running in 4x mode. Do the CCC show "Crossfire" enabled?
Yeah, it does. It's right below the Overdrive Settings in CCC. I Don't know what version to use with this setup. I'm using just 1 card right now with 8.1, i'm kinda confused on what ver. to use because there are so many mixed reviews! I was using 8.3 when I tried CFi'ng 'em.

I noticed a definate improvement over just 1 card, but Stalker didn't look right ( wierd vertical sync issues ) so I stopped and went back to just 1 and broke the h*ll outta my bridges in the process. Doh!

I don't know what the problem is, if I have just 1 card in the 4x slot it runs just slightly slower than the 16x slot. But if there bridged, the 4x wants to run that card at 2D clocks. I don't know if this is normal. Hopefuly we can kill 3 birds with one well aimed boulder.

Again, any ATI or AMD rep's out there?
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Old 04-04-08, 02:29 PM   #5
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I saw a review a while back comparing 8x/8x, 16x/4x, and 16x/16x. I recall there being a hit, but it's not very bad at all. Y'all should definitely see fps improvements if you add a 2nd card to 965 or P35.

Use 8.2 or older with WinXP, and 8.3 with Vista or CrossfireX (2x HD3870X2's).

Also you only need to use one bridge.

Edit: here's P35 vs 975X
http://www.anandtech.com/video/showdoc.aspx?i=2990&p=1
Edit 2: this is the original article I had read
http://www.bit-tech.net/hardware/200...8_versus_p35/1

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Old 04-04-08, 03:31 PM   #6
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Most crossfire systems will run with two bridges, but it doesn't help, and it may cause instability. The second bridge would be for a quadfire setup.

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Old 04-04-08, 07:39 PM   #7
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You should bump the PCI-E bus a bit to help compensate. Maybe to 110 or so.

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Old 04-05-08, 01:56 AM   #8
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Ok, solid advice so far.

Is there a prefered set of ports to use ( since their is 2 sets )? I guess someone would have said so if there was, just making sure though. Thanks so far for the input!!!!
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Old 04-07-08, 12:28 AM   #9
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I'll toss in my two cents on this one.

I am currently running a CF setup of two 2900 Pros on a P965 chipset (16/4x). Running at 4600mhz on the E8400 and 822/900 I got 19203 marks in 3d06. I can get some more out of these cards with a BIOS flash but I'm still a little nervous about it.

http://service.futuremark.com/compare?3dm06=6019719

I had some setup troubles at first but now everything works 100%.

I have no clue what I would net on a full 16/16x board tbh, but I'm quite happy with my scores.

If anyone would like me to run any tests let me know, I'll see what kind of comparisons I can make on this setup to help you guys in your decision making.

For what its worth, I'd get the second 3850.

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Old 04-07-08, 01:38 PM   #10
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Quote:
Originally Posted by satandole666 View Post
I'll toss in my two cents on this one.

I am currently running a CF setup of two 2900 Pros on a P965 chipset (16/4x). Running at 4600mhz on the E8400 and 822/900 I got 19203 marks in 3d06. I can get some more out of these cards with a BIOS flash but I'm still a little nervous about it.

http://service.futuremark.com/compare?3dm06=6019719

I had some setup troubles at first but now everything works 100%.

I have no clue what I would net on a full 16/16x board tbh, but I'm quite happy with my scores.

If anyone would like me to run any tests let me know, I'll see what kind of comparisons I can make on this setup to help you guys in your decision making.

For what its worth, I'd get the second 3850.

I started my CF setup today and can't figure out how to overclock both cards, or for that matter get the 2nd card off of it's 2D clocks.

I tried following a guide on how to do it and it failed. The 1st card can run at whatever it can handle and the second stays at 509/520 or something. I can both fans at 100% though.

Is this because the 2nd card is on a 4x bus or because of drivers? I'm using 7.11 right now and it runs better than 8.1 or 8.2. The latest versions also have the 2nd card at 2D clocks also.

Any experience with this problem or is this just how crossfire runs? I was under the impression that as long as the DDR and GPU's are the same, or close, they would match each other or the first would undelclock to match the 2nd.

Thus if my Sapphire runs at 745/1000 3D and is #2 @ 4x, and the Diamond runs at 820/1075 3D and is #1 @ 16x, the Diamond would under compensate for the slower Sapphire and they would both run at 745/1000, right?

Oh, and i'm getting at the most 15,900 on 3DM06 on CF.
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Old 04-07-08, 03:42 PM   #11
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Open services.msc & Disable the ATI Hotkey Poller, then reboot. You should be able to overclock both cards after that.

Nice 3dM06 score

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Old 04-07-08, 03:55 PM   #12
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Bump, I'm also interested in this for my IP35 PRO.

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Old 04-08-08, 12:04 AM   #13
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Quote:
Originally Posted by JLK03F150 View Post
Open services.msc & Disable the ATI Hotkey Poller, then reboot. You should be able to overclock both cards after that.

Nice 3dM06 score
Thank you, I managed to reach about 16,249, but lost the "magic combination".

By this I mean I'm about sick of trying to figure this damn Crossfire thing out and am selling my extra 2900XT. Seriously. Who wants to buy it?

ATI has some srious problems when it comes to predicting how your system is going to react to minor changes in CCC and/or whatever program you are using to control clocks and fan speed.

Ok, BioShock looks and runs great, but it did before CF too . Stalker took a HUGE dive when it came to CF, even when it was disabled! I didn't try any more. Why? I was too busy trying to get it to run correctly!!!!!!!!

Couldn't really get a solid average out of this configuration. Seems like 7.11 works best as far as ATI goes, but Riva and ATI Tool .27 b4 are hard to use along with CCC with CF enabled. Fan speeds always dropping back down to default on the main card, the 2nd card took to the fan speed change just fine and stayed "saved" on 100% duty.

Just WAY TOO MANY things to keep checking and changing and monitoring and tweaking. Too many variables and mixed results. I don't know if the problem is just me or my setup. I've seen Commando's advertised as 2x16x PCI-E and 16x/4x? Mine seems to be 16x/4x. Maybe that's it?

These cards run GREAT by themselves, but together they have been just a headache and a waste of time and money.

Before I put this card up on E-Bay, i'll offer it here, if that's allowed.

One Sapphire HD2900XT 1GB PCI-E Video Card. Cleaned, well maintained, never put through horrible torture. I will also re-applie the GPU TIM with Shin-Etsu X-23. I can guarantee this card is in great condition, I wouldn't sell a half cooked card. I've had it for less than 2 months and it was bought new.
I have all the cables and everything else that came with it.

Any serious offers can just send me a private message, or leave one here?
However you wanna do it, but all payments are through Payapl. I'll wait about a week and then i'll put it on E-Bay if I haven't recieved any serious offers. They are kinda hard to find and still sell for $400 or more, I want to sell for alot less.
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Old 04-08-08, 07:20 AM   #14
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I'm on my 2nd crossfire setup. I had 2 x1900XTs and now I have 2 3870s. It does take a lot of extra effort to bench well, but I found leaving them close to stock for gaming was fine. I also keep the 3D tab in CCC set to Balanced. The only game I had trouble with was Crysis Demo. I saw a 10-12 fps increase with cfire disabled. I read there's a patch to fix that in the final release too. Stalker may have similar issues.

I was recently told the best method of clock and fan control is BIOS flashing. I'm going to flash my 3870s tonight & see how it goes. The newer utilities make it a lot easier than it used to be.

OCF has a Classifieds Section, which you should have access to after 100 posts & using an ISP e-mail address. Go to the Home forum view & scroll down to the bottom. It is against the rules to post items for sale outside of that section.

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Last edited by JLK03F150; 04-08-08 at 09:00 PM.
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Old 04-08-08, 07:48 AM   #15
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Quote:
Originally Posted by Sarsbaby View Post
Before I put this card up on E-Bay, i'll offer it here, if that's allowed.

One Sapphire HD2900XT 1GB PCI-E Video Card. Cleaned, well maintained, never put through horrible torture. I will also re-applie the GPU TIM with Shin-Etsu X-23. I can guarantee this card is in great condition, I wouldn't sell a half cooked card. I've had it for less than 2 months and it was bought new.
I have all the cables and everything else that came with it.

Any serious offers can just send me a private message, or leave one here?
However you wanna do it, but all payments are through Payapl. I'll wait about a week and then i'll put it on E-Bay if I haven't recieved any serious offers. They are kinda hard to find and still sell for $400 or more, I want to sell for alot less.
Create a listing in the classifieds.

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Old 04-08-08, 07:51 AM   #16
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Quote:
Originally Posted by satandole666 View Post
I'll toss in my two cents on this one.

I am currently running a CF setup of two 2900 Pros on a P965 chipset (16/4x). Running at 4600mhz on the E8400 and 822/900 I got 19203 marks in 3d06. I can get some more out of these cards with a BIOS flash but I'm still a little nervous about it.

http://service.futuremark.com/compare?3dm06=6019719

I had some setup troubles at first but now everything works 100%.

I have no clue what I would net on a full 16/16x board tbh, but I'm quite happy with my scores.

If anyone would like me to run any tests let me know, I'll see what kind of comparisons I can make on this setup to help you guys in your decision making.

For what its worth, I'd get the second 3850.
For comparison purposes to see how running 16/4 bottlenecks compared to 16/16, see Brolloks post here. In summary, his CPU is 270MHz slower then yours, and his cards core is 20MHz slower, and his score is only 50 points less. That would prove to me that the 4x lane does indeed give it quite a performance hit.

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Old 04-08-08, 08:02 AM   #17
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Sars,

http://www.ocforums.com/announcement.php?f=66&a=5


Read this again.. if you even read it at all


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Old 04-08-08, 08:58 PM   #18
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Sars,

http://www.ocforums.com/announcement.php?f=66&a=5


Read this again.. if you even read it at all


No Selling Outside of classies, No Classies Access if you have a non-ISP email, also no links in your signature.
Yes, i've read that before. Forgot about that rule. Sorry.
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Old 04-10-08, 01:51 AM   #19
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Quote:
Originally Posted by ghost_recon88 View Post
For comparison purposes to see how running 16/4 bottlenecks compared to 16/16, see Brolloks post here. In summary, his CPU is 270MHz slower then yours, and his cards core is 20MHz slower, and his score is only 50 points less. That would prove to me that the 4x lane does indeed give it quite a performance hit.
I'll get some info from Brolloks and see if I can do a 1:1 comparison to isolate the PCI-E lanes.

For now, my cfx is definitely broken. I tried to install the 7.11 drivers and it quit working. It doesn't help that my XP install is 2 years old either.

I'll setup a fresh install and get 7.11 Cats installed and working this weekend and I'll get some info from him to try a comparison.

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