If you are looking for a fast, but energy efficient AMD CPU you´ll probably have heard about the Opteron 3300 series. The Opterons – formerly used only in server systems – are nowadays fully compatible desktop CPU´s using the common CPU socket AM3+. This socket is also used by AMD´s FX & A-Series CPU´s and a whole bunch of mainboards are available. The only problem is – most mainboard manufacturers only refer to the FX & A-Series in their CPU compatibility lists and you´ll probably not find any information about the Opterons.
So I picked two 3300 series Opterons for a short test with the very popular Gigabyte GA 970a UD3 Rev. 1.0 mainboard.
The Opteron 3320 EE is the most energy efficient AMD quad core CPU currently on the market with a TDP of only 25W. The Opteron 3350 HE is the second most energy efficient AMD quad core CPU with a TDP of only 45W. While the 3320 operates at 1.9 GHZ, the 3350 operates at 2.8 GHZ.
Both CPU´s work fine with the Gigabyte GA 970a UD3 mainboard but only if you have the latest BIOS installed. In my case this was BIOS version F7 (2012.10.22). One important note: the BIOS can not be updated with the Opteron 3320 or 3350. You´ll need an older CPU that is already supported by your current BIOS version. I used an AMD Sempron 145 (Socket AM3) for updating.
Gigabyte GA 970a UD3 Overview: http://www.gigabyte.de/products/product-page.aspx?pid=3907#ov
Gigabyte GA 970a UD3 BIOS Download: http://www.gigabyte.de/products/product-page.aspx?pid=3907#bios