crossfire 3870 enabeld or not need to know

I have a 2 3870 in crossfire but I have read that some people dont have it engaged and that there nt in
crossfire mode I have enabled crossfire in the ccc and my 3dmark score goes up but in the ccc it onle shows 1 gpu
but in the device manager on my computer shows 2 3870 so wtf is going on also the second card is in a pci 4x slot
is that going to kill my performance would appreciate any help.

q6600
p5k deluxe
2gigs 6400
2 HD 3870
antec 900

The second slot being only a quarter of the speed will certainly hit performance a bit, but im not sure to what extent.

However, i noticed that my CCC only picked up 1 card but device manager gets 2. Go into the Overdrive section and click the unlock key (as long as you dont change anything it shouldnt hurt anything!), then in the drop down box there mine picked up both cards and i could check both their temps. Its just the main drop down box on all the other CCC tabs that only shows 1.