BL460 G6 memory controller speed

[Jim Brewster]

I noticed in the BIOS setup that there's an option to set memory speed when using 2 DIMMs per channel to 1333 or 1066 mhz.

The quickspec seems to indicate that the memory speed is set automatically based on number and type of DIMMs. With 2 DIMMs per channel it should go to 1066.

What happens if I override this to 1333 in the BIOS setup?

[WFHC-WI]

Hi Jim,

The processor rules will trump the BIOS setting. Regardless of the change you make here your memory bus will be 1066 (unless you have 2x 4GB quad-ranks installed).

My guess is that this option is provided only for slowing down the bus (maybe in a cluster with non-identical hardware?) I recommend not setting it to a speed higher than that specified in the quickspecs.

Good luck!

[Jim Brewster]

Thanks for the response.

Is there anyway in BIOS or thru some utility to determine the actual memory controller speed that has been selected?

We've been running some memory benchmarks with 1 and 2 DIMMs per channnel and we don't see any performance differences.

[WFHC-WI]

I'm not sure of any HP applications that would give you this information...

I recommend using a third-party utility such as Everest, available here:
http://www.lavalys.com/products.php?lang=en

hth

[Daniel Bowers]

The BL460c G6 can actually run 2 DIMMs per channel at 1333. The Intel spec for the processor says that 2 DIMMs per channel is maximum 1066, but HP qualified it at 1333.

This is the one case where BIOS won't automatically set the speed to the maximum possible -- to do 2 DIMMs per channel at 1333, you have to set that BIOS setting. Otherwise, you'll get 1066.

Lots of info here:
http://h20195.www2.hp.com/v2/GetPDF.aspx/c01750914.pdf

[Daniel Bowers]

Oops, forgot one caveat -- WFH-WI is right; some of the lower processor speeds can't do memory at 1333. (Some can't even do 1066).

[Jim Brewster]

Awesome, thanks for info and link!

[Brian Proteau]

I had a couple questions regarding the "Memory Speed with 2 DIMMs per channel" BIOS setting.

We have just purchased DL380 G6 servers with 96GB. I specifically populated it with 12-8GB 1333MHz DIMMS (2 per channel) to maintain that speed.

From the link to the G6 memory doc it appears I will need to change this setting to "1333 MHz Maximum" in order to realize these speeds.

Is that all correct?