Alienware M18X R2 Memory Beeps with 32GB 1866Mhz Ram

Hey all!, I created a problem, where one was not before on my Alienware M18X r2. I got a good deal on new A-tech DDR3 32GB (8GB X 4)1866Mhz ram. I was running 1600Mhz ram, upgrade to 1866Mhz ram. At 16GB with the two slots under keyboard filled, laptop boots and reads 16GB of 1866Mhz. Great, but when i fill the other two slots on bottom, i get the beeps. Tested new ram is good. I swapped everything around, trying 3 sticks, 4 sticks, ect of the 1866. I can run 3 of the 1866 sticks, and one of the old 1600 for reduced speed, but all 32GB reads.. so slots must be good.. Went into Bios, set memory speed, installed the 32GB of 1866 no difference. So currently im running the 1866 under keyboard, and 1600 on bottom. all slots all full, stable 32GB. Should i just forget about it? is this a easy fix im overlooking, or is there some kind of hardware limit on the Alienware m18X r2 that it can only run 16GB @ 1866 or 32GB @ 1600?
Thanks!!

 

Seems like there's a conflict somewhere causing them not to work on all 4 slots at the higher rate. It doesn't seem like a clock issue since bother 1600/1866 appear to be working in various configurations except when all 4 slots are filled.

I would probably just do a 2x16GB setup with 1866 and put them into the slots in the chassis vs dealing with the keyboard slots for ease of access. I did a 32GB upgrade for $89 off Amazon but it's DDR4. Looking at the price fluctuations though right now with the chip market it might not be the best time to be buying these things like when the GPU market got hit with mining.