I mean I know how it works, but which card do I connect to the monitor?
I'm planing of using two ATI 5770's together.
I already have one 5770 running and connected to the monitor via HDMI.
Would I just buy another and put the CrossFire Bridge on the cards and have one HDMI coming from one GPU connected to the monitor.
Sorry I'm confused.
I'm also planning of using the ASUS Sabertooth X58.
You have the right idea.
You can leave your monitor attached to the card you already have in. Unplug your PC to start. Install the new graphics card in the PCIEX16_2 port next to your other card. Use the Crossfire Interconnect Cable to bridge the cards. Connect the card to your power supply with a 6-pin connector (usually has a PCI-e stamp on it), plug in the PC and boot up.
If things don't look quite right (you can't enable crossfire or you don't see two cards under graphics hardware in catalyst - Primary and Linked Adapters), you'll most likely have to uninstall and re-install your Catalyst Control Center and drivers.
1) Go to control panel->add/remove programs or control panel->programs->uninstall a program (depending on your OS)
2) Double-click ATI Catalyst Install Manager and choose the 'Express Uninstall' option
4) Run Driver Sweeper (free download from phyxion.com), check the ATI Drivers only and click 'Clean'
6) Install the ATI drivers/Catalyst software
Each time I've added a graphics card to my system, I've had to re-install the drivers.