overclock 2 different 5870 gpu card

hi, i have problem with overclocking my 2 5870 card
i can overclock just with catalyst overdrive
1. card asus matrix platinum 5870 before i use asus itracker 2 for overclock and no problem push to 980 gpu clock with core voltage control
2. card is xfx 5870 just overclock with catalyst

i try msi afterburner for high overclock dont work for me freeze, or crash
i try asus itracker - the same problem
for now overclocked with catalyst matrix on 920 clock /stock 900/
and xfx 900 core /stock 850/
i cant hit more from matrix because withouth i tracker v core control cant push more
some advice to oc this two cards in crossfire ?
IMO this 2 cards is no 100 percent compatibile together
but in 3d mark gpu score 32k
matrix 2gb mem, xfx 1gb mem

One GPU may overclock better than the other, luck of the batch. Even if it was the same brand and model they will not always overclock to the same limit, it just depends on the card.

i understand, but i can overclock my matrix to 980 core with i tracker but just single card, when i activate crossfire, i can overclock because i tracker fail with xfx you know what i mean, i just ask how to do by another way or another soft to get active vcore control,
msi afterburner freeze my system too

Have you tried just running the xfx and overclocking it? and see what its limit is. I have a good feeling it won't reach 980. When you are enabling CF your asuming that the xfx can handle the same clock as the matrix at least this is what I am getting from reading your thread. Maybe I am not understanding your post fully, sorry if there is any confusion.

I have 5770 in crossfire both are xfx one is xxx version with two crossfire connections and stock vcore 1.125v the other one is plain xfx with single crossfire connection and stock vcore 1.2v, i have tried everything to get stable overclock but no luck its incredibly hard to overclock crossfire higher than CCC allows (like with afterburner unofficial overclocking) especially if the cards arent identical, the highest i got too while being stable in all games is 950/1350 and thats after setting pcie frequency to 110, at 100 the highest i got was 930/1300, the two major factors are how similar both cards respond to voltage increase and how close chips are performace/quality wise, if one is very good and can take high clock, but the other one is very crappy and can be bearly overclocked when you crossfire them you wont be able to take full advantage of that good chip.