P55... 4GB DDR3-1600 or 8GB DDR3-1333?

[Jumpem]

Given this information, from P7P55D manual:

According to Intel spec definition, X.M.P. DIMMs and DDR3-1600 are supported for one DIMM per channel only.

 

[n7]

You can easily do 8 GB DDR3-1600 & much higher with a few BIOS settings

Anyway, i'd definitely get 8 GB over 4 GB.

Speed doesn't make much difference other than in benchmarks.

 

[Jumpem]

Originally posted by: n7
You can easily do 8 GB DDR3-1600 & much higher with a few BIOS settings

Anyway, i'd definitely get 8 GB over 4 GB.

Speed doesn't make much difference other than in benchmarks.

Explain?

 

[n7]

Examples pics in this AT articles (look for the pictures at the bottom)
http://www.anandtech.com/mb/showdoc.aspx?i=3639

I don't have a P55 mobo yet to tell you in exact wording, but it's dependent on RAM ratio.

I'm not sure how Asus is wording it, but with a BCLK of 133, you can do 10x, 8x, 6x, etc.

Obviously if you increase BCLK, you get even higher speeds.

Same concept as ratios on FSB-based Intels, just different terminology (& ratios).

I'm guessing Asus is just covered their ass by using Intel spec terms, as when you surpass official spec with all DIMM slots populated, you might to increase some voltages/tweak slightly more.

 

[n7]

Okay, maybe that's a poor way of explaining it, sorry, i do better in the BIOS than i do trying to explain RAM stuff.

Simply put, Intel's default "max" RAM speed for P55 is DDR3-1333.

That's achieved via use of the 10x ratio. (aka 2:10)

133 BCLK x 10 = DDR3-1333.

Even if the mobo doesn't have a ratio higher than 2:10, all you need to hit DDR3-1600 is 160 BCLK.

Of course, some mobos have higher ratios than than that, making it even easier.