I need some basic Crossfire advice please

I just added a second Sapphire 4870 and according to 3DMarkVantage benchmarks, I don't seem to have achieved any benefit from doing so. I'm not sure if I have it setup right. The manuals from Sapphire give little to no info on setup.

First off, the Asus M4A78T-E mobo is crossfire ready. I am using both bridges, although I started off using only one. It did not seem to make a difference whether I used one or two though. Does the direction of the bridge matter? Looking at the connectors, it doesn't look like it should. I haven't changed anything in the BIOS, and I'm not sure if I should. Device manager and CCC show both cards. The crossfire check box in CCC is checked. When i run a benchmark, it seems like only the card that the monitor is connected to gets hotter.

Am I missing something here?
Thanks in advance for any help!

I have FarCry2, and there didn't seem to be much increase in perf. if any. Oddly, with FarCry2, the fps seems to hit 60 and not exceed 60, and not drop below 58, at all times during the gameplay, as if there is a limit set.(?) I used FRAPS to get that info, if that matters. This is with all game settings cranked and although 60fps looks okay, it's the same number I got with only one card.

specs.:
CPU: AMD Phenom II 720 (2.8 GHz triple core) - OC’ed to 3.5 GHz
Cooler: Xigmatek S1283
Graphics: (2) Sapphire HD4870’s (1 Gb ea.) in Crossfire - OC’ed
Mobo: Asus M4A78T-E – 790GX / SB750
RAM: G.Skill 8 Gb - DDR3 1333 MHz
HDD: WD Caviar Black 750 Gb – 7200 rpm / 32 Mb cache
PSU: PC Power & Cooling Silencer 610
Case: Antec Nine Hundred (without stupid LED fans)
OS: Vista Home Premium 64-bit
Monitor: 28” Hanns G. – 1920x1200 res.
+lots 'o fans with a Scythe controller

I believe I do have the v-sync on. I must say I don't even know what that does!
As far as running the small ranch test bench, I only have the basic ed. of 3DMark right now, I'll have to upgrade to the advanced version and run that test tonight when I get home. Thanks for your help so far! I'm interested to see how my specs. compare to yours seeing as we have similar GPU setups.

Wow am I an ignorant noob!
Re: the small ranch test, lol - I'll have to check that out and run it 2nite. I didn't even know the game came with benchmarks! Also, you're probably right about the v-sync limiting the fps. Makes sense. Why would anyone want to use that feature?
Anyway, thanks again for your help thus far. I'm learning as I go here and I'm sure glad I have T/H and knowledgeable people to help.

Okay, ranch small, 1920x1200, 4xAA, dx10, all other settings cranked:

Crossfire enabled, GPU clock: 820MHz, mem clock: 1050MHz
* Total Frames: 2892, Total Time: 51.00s
* Average Framerate: 56.70
* Max. Framerate: 93.58 (Frame:415, 6.25s)
* Min. Framerate: 37.18 (Frame:2, 0.08s)

Crossfire disabled, GPU clock: 820MHz, mem clock: 1050MHz
* Total Frames: 2112, Total Time: 51.01s
* Average Framerate: 41.40
* Max. Framerate: 58.49 (Frame:314, 6.12s)
* Min. Framerate: 30.79 (Frame:1415, 35.01s)

The results are clear. I don't know if these numbers (the top set) are good for what I have or not, but there is a definite difference having Xfire enabled. Is this comparable to your results with similar cards?

Thanks again for the help. It is greatly appreciated.