i don't even turn on the second monitor i got because the way it's set up, i can't press the power button, and it's one of those monitors that just sits there and says "NO SIGNAL! CHECK CABLE!!" instead of turning off whenever it doesn't have a signal. so i have it unplugged and plugging it back in is a bit of a pain
not to mention i've been playing NFS Unbound a lot recently and that game is one of the few i own that utilizes 100% of the GPU so i figure having a second monitor on and playing youtube or whatever is probably not a great idea
