4 x 4gb dual channel Kingston hyper x @ 1866mhz speed issue running at 803.7mhz ?

[nail2529]

i have just got my self some new ram 4 x 4gb dual channel Kingston hyper x @ 1866mhz.

first off i have been doing a lot of research in the last hour but haven't quite found the answer to my question. i know that in cpu-z you double you DRAM frequency to reach the frequency listed on the box ie 933mhz = 1866mhz

when i have 2 sticks in its runs at the correct 937.6mhz but when i install all 4 sticks it drops to 803.7mhz

is there something really stupid that i am missing? why dose it run at 803.7mhz

i have checked all timings in bois and are all correct (CAS latency 10-11-10-30)

i have seen alot of talk about a XMP profile but im pretty sure that only on Intel mobo's?

my mobo has support for DDR3 2000(O.C.)/1866/1600/1333/1066 MHz memory modules

comp spec's
AMD FX-4300
Gigabyte 990XA-UD3 rev3

thanks in advanced

 

[kanewolf]

If you look at the memory support list for that motherboard -- http://download.gigabyte.us/FileList/Memory/memory_ga-990xa-ud3.pdf it has the following note "Note: Only one DIMM per channel is supported for DDR3-1866MHz and higher speed as using an AM3+ CPU." So by having two DIMMs per channel you can not run at 1866.

 

[nail2529]

If you look at the memory support list for that motherboard -- http://download.gigabyte.us/FileList/Memory/memory_ga-990xa-ud3.pdf it has the following note "Note: Only one DIMM per channel is supported for DDR3-1866MHz and higher speed as using an AM3+ CPU." So by having two DIMMs per channel you can not run at 1866.

thanks for the fast reply. i had missed that and now i feel silly. im looking in to upgrading my motherboard in the next few months so i shall look out for that.

thanks again 🙂

 

[kanewolf]

You really won't lose any significant real world performance when running at 1600.

 

[Tradesman1]

That is basically AMD plaing safe as they don't release true specs - i.e. I'm running 4 sticks of 2400 in my FX based AMD rig....big problem here is the FX CPUs have a true MC (memory controller) that is native 1333 (per their own BIOS and Kernel Programming Guide), the upper end CPUs (the 8xxx and 6xxx) are 'capable' of running 1866 at 1 stick per channel, per AMD but no guarantee is given, the 4xxx series is more of a 1600 max type deal, I'd try at 1600 and set the DRAM voltage to 1.6 and the CPU/NB voltage to 1.25 and try (CPU/NB may have to go higher). Another option is just get two 8GB sticks of 1600 which should have a good chance of working, 4 sticks put more stress on the MC (memory controller) and AMDs MCs aren't real strong