OC to DDR3 2133 on MSI FM2-A75MA-E35 Mobo?

[tornadobox]

Hey all,

Been out of the hardware game for a while, getting back in with an AMD APU build for 720p gaming on my TV.

I'm pretty set on getting the MSI FM2-A75MA-E35 motherboard (with the AMD A8-5600K APU), and noticed that the motherboard states that it supports DDR3 2133 memory overclocked (the exact spec is 2x DDR3 DIMMs support DDR3 2133(OC)/ 1866/ 1600/ 1333/ 1066 DRAM (16GB Max) Supports Dual-Channel mode).

So does this mean that I want to get DDR3 1866 and when/if I overclock the APU that it'll attempt to run it at 2133? Or do I want DDR3 2133 (which I assume will underclock to 1866) and when/if I overclock the APU it'll run at it's normal 2133 speed?

Lastly, would underclocked DDR3 2133@1866 run any worse than native DDR3 1866 sped'd RAM?

Thanks!

[yvesj]

the default is 1333 .now to oc to 2133 you stick have to be 2133 period .
i know i do have a fm2 board when i check the ram was on default at 1333 so i try 1866 but no go because my stick was only 1600 so i did 1600 np problem .
this is how my asrock board work anyway

[WaitingForNehalem]

All it means is that the 5600K supports a maximum speed of 1866. If you run the DRAM at 2133 you would technically be overclocking the IMC.

[Soulkeeper]

You'll have to up the bclk to 133 from 100 with the 1866 mem divider selected.
If that MSI fm2 board is anything like the 3 different fm1 boards i've tried you could run into other problems as well, such as vga no longer working and losing the use of the first 4 sata ports.
Although, to your question, I would still personally suggest getting 2133 mem.
There are many good memory choices now (mushkin, gskill, kingston hyperx, samsung'1600 stuff overclocks well', etc.).
I'd suggest getting everything stable at 100bclk 1866 mem before even attempting 2133 however.

EDIT: Apparently some of the stuff I mentioned above has been fixed since fm1. upto 2400 mem speed with 100 bclk is possible according to that link.

good luck

[tornadobox]

Thanks for the replies guys...

...I wouldn't be underclocking the 2133 just to get tighter timings, it just so happens that the 2133 memory is a few bucks cheaper than the 1866 memory:

G.SKILL Ripjaws X Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 2133 (PC3 17000) Desktop Memory Model F3-17000CL11D-8GBXL @ $34.99 through today only

vs.

CORSAIR Vengeance 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1866 (PC3 15000) Desktop Memory Model CMZ8GX3M2A1866C9B @ $39.99

Is it cool to just overclock the IMC just to run the 2133 RAM without overclocking anything else? Would it be worth it to do that (vs. just running straight 1866 RAM at 1866 speed)?

The timings on the 1866 RAM seem better (9-10-9-27) vs. the timing on the 2133 RAM (11-11-11-30) but I don't actually know if it really is any better since the 2133 is faster.

[Soulkeeper]

much of the gskill and mushkin 1866/2133 have the same hynix chips on them so you can generally clock them similar with comparable latencies.
ie: 10-11-10-28 at 2133 or 9-10-9-27 at 1866 with 1.5-1.55v would be reasonable
the hynix datasheet says +/- .075v which is inline with the jedec statement of "1.575 volts should be considered the absolute maximum when memory stability is the foremost consideration".
They started selling 11-11-11-30 kits recently, likely to decrease the chance of people having problems/returns.

That corsair CMZ8GX3M2A1866C9B might very well use the same hynix chips, but I am not certain of this. The heatsinks are definitely larger if that's what you like. Most DDR3 don't get very hot (I removed the heatsinks from mine and still overclock them fine).

I don't think you'll have any problems with your idea.