you are late, if you have to ask that question, the answer is to NOT BUY.
I have the money ready, i would hate to lose it on nothing, but still, despite the current un-stable situation there is hope in the future right?
I'd say buy in, but start small. You say you have a gaming rig, then why do you need an 890fx board? If you want to use it as a pure miner, buy a VERY cheap mobo with 2 pcie slots or even 1 x16 and 1 x1. get a sempron 140, you dont need a dual core. And unless you care about your power consumption, don't get a 5770, get a 5830 or even 6950 (in the US 58xx seem to be rare I hear). You could also consider getting a second hand 775 board with a pentium, or 939/AM2 board. Worst case, you will lose much less than with your setup.
Otherwise, you could build a gaming rig with good mining GPUs, mine for a bit and then sell it to a gamer for good cash and little loss...