Hi there,
OK I know the situation is difficult and it is made so much harder by the information that is being given out by AMD and the Mobo Manufacturers.
You can run your RAM above 1333 Mhz but there is, according to AMD, the risk of system instability. I have a 1090T and have been able to get 8 gig of 1600 Mhz RAM running in Unganaged mode without issue. (Corsair Dominator 2 x CMD4GX3M2B1600C8 (8 Gig)). The real problem for AMD and motherboard manufacturers is the variance in RAM modules and no-one can state with any degree of certainty that what works for one system at 1600 Mhz will work OK in another rig. AMD do not advise running RAM above 1333 Mhz with the AM3 CPU's but it is not something they want to shout about for obvious reasons.
I want to run 8gb (4x 2gb) so to run 8gb do I need to stick to 1333mhz? (that would suck!)
Not really, the actual perfomance difference between 1333 and 1600 Mhz is really not that noticable in the real world and, if you are getting a 1090T CPU with unlocked multiplier, boosting the speed of the CPU and leaving the RAM at 1333 Mhz is actually a better way to go for improved system performance. If you are using 1600 Mhz RAM, downclocked to 1333 Mhz it does give you the benefit of some extra headroom to play with when getting the extra speed from your CPU.
If you wish to use 1866 Mhz RAM you are limited to only 2 sticks of RAM in Unganged Mode (1 stick for each memory controller) So. at the moment, you would probably be limited to a Max of 4 Gig.
If you put any RAM modules in above 1333 Mhz the system will automatically drop them back to the default settings. You will have to manually adjust the timings to achieve the correct speed.
Should I go for 1866 ram?
Personally I would say no. Check for 1600 Mhz RAM on the QVL and stick with that.
And can I run 8gb at 1866?
Not unless you can find 4 Gig RAM modules the answer to that is also no.
Hope this helps clear things up a little.
