Multi Gpu is a more sophisticated technologie than that. It's not like throwing a GPU more to get 100% gain of fps. First thing about multi GPU technologi is about the ram. In your case you probably got two 3870 X2 with 1 gig memory each. In fact, you may consider your card as 512 mb of ram beacuse each video card has to have the whole set of textures loaded in to render the image. Be carefull when you set texture details in games beacuse adressing more texture memory than you've got will make it swap to system memory and you'll loose plenty of fps in the process. Most of the time, you only need to lower texture details with all other options cranked-up to get good performances. The second thing is about the rendering methode. in a Crossfire or SLI config each GPU will render a part on the entire image. In some case, all the job would be done on a single card while the other GPU waits for the scene to be completed. I might be wrong but, there's no load balancing technology involved in multi-Gpu rendering. In fact, in first gen of Crossfire ATI tried to implement a load balancing system but it was pointless because of the ressources used by such system.
OK I get all that but even not setting textures to high what kinda quality will that add to the game. Its like your saying to get more performance lower down the settings of the game. But then wouldn't it be pointless to even have crossfire or sli if you have to lower your settings all im saying is if there is no performance gain from one card to two then what would be the reason fro anyone to even consider crossfire. Yeah its cool and you can brag to your freinds but if you have to lower setting in game to get improvement then you can do that with one card!
The textures sharpness (quality) is only one of multiple factors in general rendering quality. by adding GPU's you will add calculation possibility and that mean you be able to push Antialiasing,Anisotropic Filter, Particules and world details to higher level without compromising on FPS. With bigger screen (and resolutions) comes better chances to see the true differences between simple and Multi-GPU. For my part I got 1 3870X2 and 1 3870 in CFX on a P45 chipset wit 2.4 quad-core (same as you do). I might suggest you to overclock your CPU a bit. Especialy on Far Cry 2 and GTAIV I've seen a HUGE difference while running on overclocked frequencies (3.1). As a conclusion, your right. Ati 3870 is'nt the card of the year in 2009 but one year ago, a 4870 worth about 800$ and scored under a tri-3870 solution for about 500$ so that is what I brought home. After one year of tweaking I can say that there is absolutly no cogency in performances from games to others. Crysis (incredibly poor), COD(incredibly good), Far Cry 2 (really Nice), L4D(WOW), Fallout(passable) GTAIV(disapointed). Usually, a patch partially solve the problem in the game when anyway you've got bored to play it.
Finally, I think it's work fair enough to get stuck with it for a while. Each time I buy a new game I need to tweak the settings until I've fond the good recipe but I'm not afraid by that and thrully, it's a part of the game (Lego invented it). By the way new games make better use of Multi-GPU as Multi-core ether.
Yes all true tweaking it out is what its all about but to see your second set of gpu's idle 99% of the time is disharting. I also tried the tri-fire set up like you and still did not notice any gain of the secong gpu actually being active. As far as benchmarking well I've ran all the test read all the reviews and still cant figure out what is going wrong and why! Contacted mb company and they say video card and vise versa! I think its ATI's fault for not getting the drivers to work right without have to adjust them to our own benifit when i turn on crossfire i want to see gains what ever they are. I didnt get this setup just to stress out my psu!!! Also I am upgrading psu's going with a xion 1000watt 6 12v rails hopefully this might help!!!
crysis somewhat and suprisingly cod 1,2 use a four cores but cod4 no. really thats about it and crysis run better with 2 then 4 so its not even worth it looks like crap gotta turn the textures to low everything else can be high. I just dont know what the real issue is!
Crysis is a case by itself! far cry 2 runs flawlessly on crossfire 3870x2 on the same f... engine. Don't try to conclude anything from crysys stats. It's been program for nvidia card and this f... game works only on thoses. You wana play Crysys? grab a N6600gt It will work bether than quad 3870 for shure. The Issue is Crysys but Hey, there plenty of games out there that worth playing... don't get stuck on this one!