Oh yeah you need to enable SLI even with a single 295 for both cores to work, from driver perspective it's the same as having two separate video cards, so disabling SLI takes you right down to single GPU (though instead of disabling altogether i'd just alter the SLI profile to Single GPU Mode in the control panel)

Wow most of those addons are £20 or more I can see how that adds up!!

Where abouts are you M31? Livingston here