Memory speeds do not seem to matter...

[edro]

Sapphire Radeon HD 5750, 10.1 with ATI Tray Tools
AMD Athlon X4 II Propus 630 2.8GHz (14x200mhz)
GSkill Ripjaw 4GB 1600MHz DDR3
Asrock M3A770DE AM3
Mushkin 550W
Win7 x64

This is my new system.

One thing I can't figure out, is that my motherboard's [AUTO] setting for my RAM is 440Mhz (shown in CPU-Z).
When I manually force it higher, to say 800MHz, I get almost no performance increase at all.
According to GTA4 benchmark, I get 1FPS better.

What is the point of higher memory speeds since it doesn't appear to affect anything?
Will using higher memory speeds allow higher CPU bus speeds?

Thank you for you help!

 

[alyarb]

the clock of both the CPU and memory are determined by a multiple of a base clock frequency which usually corresponds directly to the speed of your system bus. If you aren't overclocking your CPU with a multiplier, you have to increase this bus, so your memory will have to run faster as well. I had an EVGA 680i board that could run the memory asynchronously but meh it was still a piece of shit.

You aren't necessarily buying RAM for it's faster "speed." You simply are buying the flexibility to run at higher speeds so that you can overclock your system bus necessarily higher without strapping the RAM down to a super low multiplier. For example, on my Gigabyte P45 board, to run my bus at 436 Mhz, the only reasonable FSB:RAM straps available would be something like DDR2 720 or DDR2 1075. I'm using DDR2 1066 so really that 1075 is perfectly within reach and I can run both at 5-5-5-15, 2.0v. I'd rather run that than 720 Mhz. My numbers could be a little off and I'm not going into my BIOS to check (really the board comes with lots of other memory straps to choose from) but this is the general idea.

You definitely don't need to worry about buying memory to run at insane speeds. read this article and you'll see that there are no general cases, only specific cases, where you get a couple of percent from having faster RAM.
http://www.anandtech.com/memory/showdoc.aspx?i=3589&p=1

Tom's Hardware did the corresponding article on the Phenom II, and the story is the same. The sweet spot for AM3 and 1366 is DDR3 1333 and 1066. These are the speeds of most affordable kits and generally the higher-clocked higher-latency modules offer less performance, but it's mostly a wash with WinRAR being the only exception. It takes a large disparity between the RAM and CPU speed before it will begin to present a bottleneck, but flexible RAM and the correct multiplier is what facilitates you to remain far away from this bottleneck ever becoming serious. It is a pity that neither Tom's nor Anandtech had any test data for yorkfield above 4 GHz because that is when 700 Mhz memory (in my case) is going to make you wait.

 

[edro]

Thank you!

Here is Tom's article.
http://www.tomshardware.com/reviews/phenom-ii-ddr3,2319.html