Hi, I'm running a Radeon HD 7770 with the latest driver. I'm on a Windows 7 64 bit system. I'm attempting to use three monitors but when I plug in the third both the Windows display options and Eyefinity give me the option to turn on two of the displays. When I try to set the third to either mirror or extend it says it can't save the changes (or in Eyefinity it won't even let me click it). I've got one plugged in from the DisplayPort with an active DisplayPort to DVI cable. Another is plugged into the DVI port with a VGA cable and an adaptor. The third is plugged in to the HDMI port with an HDMI to DVI cable. 

All of the monitors work, I can shuffle them around in the settings. I just can't get all three to work at once. 

I'm not sure what brand my PSU is, but it's 900 watts. I've got 8GB of RAM. Intel i7-2600 @ 3.4GHz for a processor. Not sure what motherboard I'm on, but if you think that's relevant I'm sure I could find out.

Any Suggestions welcome. 

Try useing less adapters? specifically the VGA one. 

I5 3570K@4~5.0ghz: Gigabyte GA-Z77X-UD3H:Corsair Hydro H70w/Delta 240CFM Fan: 16GB Corsair Vengeance DDR-3 1600: 2 XFX Radeon 7950 @ 1150/1575 : Corsair AX 860 PSU: x2 WD Black 1TB HDD's: 90GB OCZ Agility 3:CL X-FI:Corsair 500R Arctic White Edition:3 22inch Asus monitors Eyefinity @ 5294x 1050(bezel comp) : Alienware Tact-X Keyboard: Naga Razer gaming mouse:Corsair Vengance 1500 Headset .