Hi XLR,
I check here :
http://www.gigabyte.com/products/product-page.aspx?pid=3449#spGA-X58A-UD3R (rev. 2.0) Specifications
6 x 1.5V DDR3 DIMM sockets supporting up to 24 GB of system memory(Note 1)
Dual/3 channel memory architecture
Support for DDR3 2200/1333/1066/800 MHz memory modules
Support for non-ECC memory modules
Support for Extreme Memory Profile (XMP) memory modules
So you are right with your number of stick of ram.
I imagine you place 4 sticks on Dual Channel. And 6 sticks on 3 Channel...
EDIT01:
I see this:
http://www.valueram.com/datasheets/KVR1333D3N9_4G.pdfbut I do not have a similar information about your Corsair RAM.
About corsair:
I just view in the specs : Size 4GB Kit (1 x 4GB)
Probably a mistake. Correct me if possible ... but I think it's 4x1GB.
If you mix a sticks ram, with different brands and model, you have many possibility to have problem.
By exemple, if a ram have a number of chips different. Or model of chip like 256M x 8-bit.
Gloup_Gloup