Memory not working on proper speed

[ChrisFalcon]

Hello!

I just bought an additional ram for my PC (from 8GB to 16GB) and have encountered a problem.

Previously, when PC was working on 2x4GB - it was running on 1866 mhz and suddenly when it's 4x4GB it's working on 1333 mhz. Of course, it is the same model etc.

Any ideas ? And if there would be no solution, would you recommend to stay on 16gb with lower speed or 8gb with 1866 ? I use the PC for gaming and A/V Editing.

Full specs:
Windows 7 x64 bit
Gigabyte 990FXA-UD3 rev.4.0 (F2 BIOS - there is a newer version but when downloaded from the producers site, an error pops up and says that the application is not working on x64)
GOODRAM Silver Play 4GB 1866 MHZ CL9 (4 DIMMs)
FX 8320
950 GTX
Power supplier: 650v
One HDD and one SSD

Thank you for your help.

 

[bignastyid]

The motherboard doesn't support running 4 dimms at 1866.

 

[Tradesman1]

No guarantees with mixed DRAM, can try manually - prob at 1866 - 10-10-10-28, 1.6 DRAM voltage and set CPU/NB voltage to 1.25 ---- may also need an OC on the CPU to help the MC (memory controller)