Thanks for your input.  

Both servers have a PERC 6/i with 6Gbps drives.  I wouldn't think it would matter since the issue is purely memory with no disk i/o.  We only have a couple of dell servers, so my experience with them is low.

Dell support told me "Downgrading the Bios may cause the newer system fail post. ".  

The reason I suggested a bios change was to match the new-slow system with the old-fast system.  I won't upgrade the old system, so downgrading the new one was the other option.

There just isn't much difference between the two servers.

Sorry ... I saw "transfer" and assumed you were doing disk tranfers, failing to see how it was a memory configuration issue :)  Also, just an FYI ... the PERC 6 is a 3Gbps controller, so if you move on to disk benchmarks, go in with the right expectations.  My bad for not paying attention.  I'm not sure what else to suggest short of swapping components to narrow it down ... however, it is clear that your configs should not have such a disparity in performance.  Have you tried reinstalling, in case something goofy happened during the install?

"Dell support told me downgrading the Bios may cause the newer system fail post."

You have the same chance of causing the system to fail post when upgrading the BIOS as you do downgrading.  It is under warranty, so even if it does cause an issue, they will replace your board.

" you can't downgrade the firmware if 'old' turns out slow like 'new'"

Sure you can.  You simply run the older package, saying yes I know that this is older than the current version.  However, I fail to see how that would help your situation :)

One thing you didn't mention is WHICH PERC they had.  I might assume they have the same PERC controller, but it can make a huge difference when comparing H200 to H700/512 to H700/1GB to PERC 6/i, etc., so I'd hate to make assumptions on such an important detail.  I might also assume that all drives are 6Gbps?

It is on the download page of 6.0.7 under Other Versions:

www.dell.com/.../DriverFileFormats

I'm not just a benchmark snob :)  If the new system will perform like its twin brother with the same hardware, I'll be happy.

I forgot to mention that I actually did swap the RAM between the two systems, to eliminate that as a possibility.  The slow memory performance stuck with the server, not the RAM.

I originally had CentOS5.7 installed when the slow performance first came to light.  I reinstalled RHEL5.3 just to make it identical with the fast system.  I don't *think* its a linux config issue of some kind.  Both systems have straigt-off-the-dvd installs and kernels.

I also tested both with Phoronix PTS, a boot dvd benchmark, to eliminate the OS from the picture.  On those memory tests, the new system was only 17% slower.  Still a big difference for 2 servers with almost identical configs.  Thats what makes me wonder if the problem is some kind of bios/linux interaction.

Where would I find old BIOS files?  Under the "downloads" for my service tag, it just shows the 2 most recent BIOS.  6.1.0 and 6.0.7.  I'm on 6.0.7, I'll go ahead and upgrade just to try it.

Thanks for the direct link.  There isn't an Other Versions link on any of the BIOS pages I see.  If I dont get any other ideas before monday, I'll give the old bios a try.  If it fouls up the system, so be it.  I can't use it as is :)

Upgrading from 6.0.7 to 6.1.0 didn't have any effect.

The Other Versions isn't on the download page for the latest version ... just the 6.0.7 page (a "bug", I take it, that just started recently on some of these downloads).

We have a few of the R710s here, new and old 11th Gens.  I have downloaded the benchmark and will try it in the LAB on Monday

Thank you very much Hamboney.  That would be most helpful.  I am going to swap the CPUs between the 2 boxes and retest.  Dell is sticking to the proc speed as the reason.  I can't believe that going from 2.53Mhz to a 2.40Mhz procs causes the system to run at half the speed.  Hopefully the cpu swap plus  your numbers will bring some more data to the table.

Theoretically, the 2.4 (both are same specs otherwise) should only be 5% slower than the 2.53, so even if you take your 17% variance with the bootable version, I don't think the difference is justified.