Guide: AM3 CPU's Which Ram Speed is Faster and Which CPU-NB Clock is Best

I see many people asking questions about AMD memory settings and would like to post this guide as great information regarding the AM3 platform and memory. It has been very useful to me, especially because I really couldn't run 1600mhz stable. Mods you should sticky this as it is such a great read.

I did not make this guide and take no credit for it, please give a big thank you to Tony over at OCZ Technology.

Here we go guys:

With popularity growing for AM3 and people looking to squeeze every last drop of performance from their Black Edition CPU i though i would investigate the best way to set up a system and see just which method of running the memory was faster.

Most feel higher numbers = better, so 1600MHZ ram should be better than 1333MHZ ram...prepare to be shocked and pleased all at the same time!

The key to Phenom 2 performance is the NB clock or memory controller clock, it is shown in the bios on most boards as CPU-NB or memory controller and has its own multiplier adjustment all of its own.

Stock speed is 2000, but this is FAR FROM BEST...you really do need to consider 2600MHZ or higher for you to get the best from your system.
So lets see my results and i will explain where you need to focus your tweaking efforts.

1333 6-6-6-24 1T and 1600 7-7-7-24 1T but with the NB-CPU clock at 2000, 2200, 2400, 2600, 2800 and 3000 with CPU @ 3.8GHZ as this is where the bulk of air and watercooled rigs will land.
Tests are super pi 32m and AutoGK encode DVD FILM 720X480 800MB VOB up scaled to 1280x960 AVI 160MP3 sound 350MB file.

time is converted to seconds for both test, lost the decimal places off PI as they were not needed


So lets make this easy for you and drop the results on the same graphs


As you see 1333 6-6-6-24 1t is faster than 7-7-7-24 1t for super Pi but slightly slower for encoding. What you need to note though is at around 2400MHZ CPU-NB encode test both 1333 and 1600 are so close its not worth bothering about...after that 1600 is faster as 1333 memory starts to become a bottleneck.

Update May16th 1:25AM...5-5-5-24 1t hits back. you guys looking for 1800MHZ ram at 8-8-8- or 9-9-9- forget it, with the NB around 2400 to 2800MHZ 5-5-5-24 1t 1333 is where you need to be.


And finally adding 6-6-6-24 1t 1600MHZ into the graph...for me 1333 5-5-5-24 1t is best, easier to do with most ram and for me allowed an easier OC on the CPU and the CPU-NB.


Moving on now we have a another domain we can overclock called HT let us see how overclocking this has an effect on 3D performance. 3870X2 Video card, stock clocks. 3dmark vantage
CPU @ 3.8GHZ, CPU-NB@ 3GHZ, RAM @ 1600 7-7-7-24 1t

As you see 2000HT is faster by a mile than 2600HT so leave it at stock speeds...no tweaks needed

Thanks again to Tony for such a great guide

It should essentially apply the same way for ddr2. I believe 1066 is very easy to achieve on DDR2 with AMD, so you can still clock your ram higher and increase northbridge speed. I would assume the higher the NB speed the better performance you would get, being similar to the AM3 platform. It should scale similarly.

Wow those patriot sticks clock very nicely. I hope you can push higher

From what I understand, the default 2000mhz for HT Link is best. According to the last chart, the higher the HT Link is the worse the performance in 3dmark, so I assume it would be similar in other applications. You could do a quick test yourself but I don't think it will be any real world performance gains/losses. Maybe a few points in a benchmark.