I found something interesting, hoping a dell tech person can confirm.
I believe that the Dell Optiplex 790 DOES NOT support Ivy bridge, because it uses the Intel Q65 Chipset.
The 790 uses the Intel® Q65 Express Chipset. (Verified - not my question <grin!>)
I believe that the Intel Q65 DOES NOT support Ivy bridge.
The Wiki page says this:
Sandy Bridge chipsets, except Q65, Q67 and B65, support both Sandy Bridge and Ivy Bridge CPUs through a BIOS upgrade.
The Intel Website for the Q65 Express Chipset does not list any "Ivy Bridge" i7 chips.
Intel Core i7
BX80623I72600
BXC80623I72600
CM8062300834302 i7-2600 3.4 GHz, L3 8 MB
BX80623I72600
BXC80623I72600
CM8062300834302 i7-2600 L3 8 MB, Turbo 3.8 GHz
BX80623I72600K
BXC80623I72600K
CM8062300833908 i7-2600K 3.4 GHz, L3 8 MB
BX80623I72600K
BXC80623I72600K
CM8062300833908 i7-2600K L3 8 MB, Turbo 3.8 GHz
CM8062300835604 i7-2600S 2.8 GHz, L3 8 MB
BX80623I72600S
CM8062300835604 i7-2600S L3 8 MB, Turbo 3.8 GHz
www.cpu-upgrade.com/.../Q65_Express.html
What got me started on this, was a video on newegg.com about the ivy bridge processor
they listed in the video the intel chipsets that are compatable with the Ivy Bridge processors
Specifically, they mentioned H61- H67 - P67 - Z68
www.newegg.com/.../Product.aspx
I found a reference at PC Magazine also:
Only four motherboards using the 6 Series chipsets support Ivy Bridge (H61, H67, P67, and Z68), but if your computer already uses one of those you already have everything you need.
www.pcmag.com/.../0,2817,2403407,00.asp
Here is a quote from maximumpc.com
However, not all chipsets will make the Ivy Bridge cut. Intel has intentionally left out support for the business chipsets Q65, Q67, and B65 while supporting consumer H61, H67, P67, and Z68. Why leave some out? Intel believes the day of an IT shop getting down and dirty and upgrading processors in an office-drone PC are long gone, so there’s just no reason to expend the resources on unnecessary support. Besides getting the latest core technology from Intel, switching to Ivy Bridge on older 6-series boards should also give you PCIe 3.0 support on some slots.