Why is my new 8GB DDR3 1866Mhz performing worse than my 4GB DDR3 1333Mhz (Gaming)?

[304FV]

So, I have the a10 7860K with 4GB of DDR3 1333Mhz Ram. Recently upgraded to 8GB 1866Mhz and its way worse. (20 FPS average)

I don't know what to do...

 

[Tradesman1]

What's the DRAM running at - check with CPU-Z in the memory tab what the freq of the DRAM is, it will be half of the data rate - i.e. 1866 should show as 933

 

[304FV]

It's 931.4 most of the time

 

[Tradesman1]

It's running at 1866 (+/-) then. What's the old DRAM, if it was 2x2GB then would have been running in dual channel which is better than single channel mode

 

[304FV]

Yes it was dual channel... is that why 4GB of RAM are performing better than 8GB?