Can anyone confirm Windows 10 will run on this computer? Dell’s website says that it has not tested…nor will develop drivers for Windows 10 on this model:
http://www.dell.com/support/home/us/en/04/product-support/product/optiplex-790/drivers
We don’t have a solid answer on the Win10 upgrade for this one, either. Sorry. 
Also can this unit be upgraded w/USB3.0? (Powerful unit but needs help in allowing users to maximize the power and speed.)
Regarding Win 10 it should be a snap. Any computer that runs Vista or later can handle it and it will be a huge improvement. I have upgraded 13 systems the oldest being a Core 2 Duo Alienware M17x (pre Dell) laptop from 2009 and it runs like a charm.
A friend has 2 PC’s that have older processors. An i5 750 and i5 2400. Both are running Windows 10. One of them is a Dell Optiplex 790 descktop.
This Woot system has a 64 bit OS on it already, so you should have no problem. BTW, Windows 10 setup has a CPU feature that checks to install. If it’s not enabled the checks fail.!
Anyone know how hard it would be to add a wireless card to this and if so what one?
Bought 4 of these computers. 3 of 4 had a bad HD. thanks woot!!!
ASUS usb n10 will work fine. any wireless add-on really.