Crossfire problems

I have 2 HIS Radeon 4870 1GB vid cards that just don't seem to get along. My mobo is a ASUS P5B Deluxe, which is crossfire ready. I know the mobo runs @16x/4x but even with any video cards in crossfire mode you should see some improvement in performance. WRONG! not me. While playing WoW @ full settings, highest resolution, I get awesome FPS with 1 of these monsters (FPS 100-150 average) BUT, when I add the second my FPS seem to be normal when im standing still and looking around but, once i take 1 step they drop DRAMATICALLY to like 20-26 fps, which is very confusing to me. I really don't think it's the cards because I've swapped both of them out to see if it that was the problem but, I get good FPS with either of them. What I wanna know is why? Why are my fps dropping so damn much, why is there such a decrease in performace when I play WoW. I ran a 3dmark06 bench and I can see that my score was 2k higher than when I had 1 card (before 12106, after 14126), but I just don't understand why it hates WoW. If any of you genius out there has any solution please throw em at me please, I hate to see my second 4870 just sitting there not being used at all. My opinion is the motherboard, but that's just me, I've had this mobo for 2 years now. If you need anymore info just let me know.

Does WOW support Crossfire? Maybe there is some sort of confliction with crossfire in WOW

Here are my specs:
Core 2 Duo 1.8 Allendale (2.8Ghz) (old)
4GIG G.skill RAM (new)
Asus P5b deluxe Mobo P965 Chipset (old)
Corsair 750W xfire/sli ready PSU (new)
Maxtor 160G harddrive SATA
Average CD/DVD ROM
2 HIS Radeon HD4870 1G Video Card (2nd not currently installed)

I'm @ work at the moment but, when I get a chance I'll do a full uninstall/install of the drivers, run driver cleaner pro and install the latest drivers and see what happens. I also enable the Asus C.G.I function in the BIOS so the cards can talk to each other.

I'm currently in the process of buying a new CPU and Mobo pretty soon, but I just want to know whats up with the system I have now.

I know my CPU is holding back the performance of the cards as well as the mobo, but that being said there still shouldn't be such a severe decrease in performance when I play WoW. I have Crysis Warhead and FarCry 2 im gonna install when I get home and see if it theres a drop in performance on those games. If that's the case then its most likely has to be driver problems, outdated CPU and mobo or maybe something else I can't think of. I currently have the latest BIOS installed also, not sure if that can be a problem too.

If you have anymore theories from the info I just added please shoot em at me. Oh and I also have the latest ATI drivers currently installed too.

ok so then the major problem is just outdated hardware, im just glad its not my cards cuz i hate going through the RMA process. Thanks for the help you all, very much appreciated.

You were right!

I see now, but beside that fact, I did some snooping around the web and found out that WoW doesn't support crossfire that well because of the new patches and the SHADER engine. There are no fixes as of yet until ati comes out with a new catalyst driver but ppl have been tweaking with the game found a way around the problem.

I'm gonna try it out later on when I get home today. Surprisingly enough others have been having the same problem I've been having with the same video cards and the 38xx series. Severe stuttering, massive decrease in FPS, and when they turn off crossfire, everything works fine.

I installed Crysis, and Oblivion the other day and saw no problems running them with crossfire. I ran Crysis Warhead on max settings with 1280x1024 res, and I got around 30-40 FPS on average,lowest 24. Oblivion ran awesome with max settings and max resolution 1680x1050 I think it was. So yea its been WoW this whole time, thats a load off my shoulders. You guys have been great and very helpful, Ill be back with more questions and concerns, you can count on it.

I'm thinking about buying a p45 board for an upgrade, its reliable and very affordable. I WISH i had the money to get me a good x38 or x48 for the dual PCI 2.0 @16x but, its just a little above my pay grade with bills and all. So here tell me what you guys think of this board, if you have anymore suggestions let me know.

[url][http://www.newegg.com/Product/Product.aspx?Item=N82E16813128358][/url]

Along with a C2D Wolfdale 8400 CPU.

These 2 things are all i really need for now. Everything else is up to date, new PSU, new vid cards, new RAM, only 2 things holding me back from my awesome to decent rig.