DDR3 Spec's

[ROA44]

I'm looking at an ASUS M5A99FX PRO R2.o Motherboard and working out which Memory to purchase. the Data says the board supports up to DDR3 1333MHz. Is the EG. DDR3 8G kit 1600, 2133, 2400 coding a different value, description or grading to the 1333 coding. if that makes sense.

[arthurking83]

The 1333 Mhz rating is (say in this example) the lowest common denominator.

That is, the motherboard will only work with RAM that is 1333Mhz or faster.
I don't think you can get slower DDR3 RAM anyhow. (not sure on this tho).

Usually the premium on slightly faster RAM isn't all that much, so try to get it slightly faster(as long as it's not costing you a fortune!)

I'm pretty sure that in default setup in the motherboard's BIOS setup, the faster RAM will be set to operate at the 1333Mhz speed that the board needs.

BUT! you could easily tweak that setting in the BIOS setup to take advantage of the increased speed of any faster RAM you get.
There are limits to doing this tho .. so if you think that you can get a lot more performance just by getting 2400Mhz RAM and setting it so on the motherboard's BIOS .. it doesn't work that way.

Hopefully all that made some sense.

summary: if you get faster rated RAM(eg. 2400), it will work on your slower rated(eg. 1333) motherboard.

[ameerat42]

But older ram has the premium $ attached, supposedly because it's harder to get.

[fillum]

Specs show...

4 x DIMM, Max. 32GB, DDR3 2133(O.C.)/1866/1600/1333/1066 MHz ECC, Non-ECC, Un-buffered Memory
Dual Channel Memory Architecture

so you should be fine with any speed listed (assuming the OS / CPU restrictions listed on the link don't apply). The clock speed doesn't tell the whole story, as the higher speed ram often tends to have higher latency (takes more clock cycles to access ram data). Currently best price/performance probably (?) 1600 or 1866. With dual channel you should get a performance boost by installing 2 'half-size' sticks (in the appropriate slots) rather than a single stick, so for 8Gb install 2 x 4Gb sticks, for 16Gb install 2x 8Gb, etc...

But older ram has the premium $ attached, supposedly because it's harder to get.

Hmmm...mutton dressed as ram perhaps ?


Cheers.

[ROA44]

Thank you guys MSY's systems are showing 1600MHz fitted so should be OK sounds like it applies to AM3 series 100 & 200 CPU's