Bios only showing 4gb with 8 installed

[Railroader]

4Gx2|GSKILL F3-1600C11D-8GNS R Memory
GIGABYTE|GA-F2A88XM-D3H FM2+ R Motherboard
CPU AMD|TA6-5400K 3.6G 4M FM2 R
8 GB Memory
Windows 8.1 64 bit
The bios only recognizes 4gb as does windows, Have updated the bios to latest version
reset CMOS,
Should Note: cannot boot computer with only one memory module. I thought it should boot with only one, we swapped out each one, it will not not boot with either one, will boot with both installed Any help would be appreciated. Thanks

[GSKILL TECH]

Send them in for RMA replacement or exchange for a different model to see if it works better.

Are you using the same color slots furthest away from the CPU?

[Railroader]

Send them in for RMA replacement or exchange for a different model to see if it works better.

Are you using the same color slots furthest away from the CPU? Yes

No , it is not overclocked

The computer should boot with only one module should it not? we do not have any extra ddr3 modules, lots of extra ddr2

[GSKILL TECH]

Yes, the system should boot fine with one module installed.