With any OEM case you MUST check with a measure and make sure the card will fit. More often than not there's no problem...But sometimes there is.
An 850 Watt PSU is nearly nuclear overkill for a single card system, drop back to 600 Watts with dual 6+2 pin PCI-E leads from a decent maker and you'll be fine.
TT are making some decent units now but also consider those from: Antec, Silverstone, Seasonic, Corsair, FSP, EVGA and XFX.