Those became available in the US in in April. Other regions have had them longer I believe.
The geeks over at JG seem to be of the opinion that these units might have heat issues due to the restrictive nature of the intake grill, however, considering the fact that worst case scenario you need a 550w unit to power either of those cards, being as that unit is advertised as an 850w unit (As mentioned we can't verify due to no reviews and nor real sample history) I'd guess that heat shouldn't be a factor as you'll likely get nowhere near the peak capacity of that unit IF it can actually sustain it's rated wattage. Likely, it can, but you never know. I'd second the opinion that you should be totally fine.
I would not however try running a dual card configuration with either of those card models with this power supply even though technically it's rated capacity is enough to allow it. Then, it would be likely that heat might become an issue.