They have more strange explanations on that site though. I too found this to be the most silly explanation why the memory controller only handles 24GB of memory. You need to read past that. This plus the OWC blog article are the only two things I could find about the 24-32GB story.
I don't take DigiLloyd's site all that serious when it comes to hardware (take a look at his storage configurations if you know how to handle RAID). BTW, I'm not the only one.
As per software such as Photoshop, ..., he seems to be more knowledgeable on.
Than the SP models should be able to address the 228GB as the DP cpu's do. I'm not too sure about that. It does make sense in one way: just one memory controller for all their cpu's. I just don't think it is that easy (why not create 1 cpu and disable stuff like cores on it...it's not feasible when you look at the financial part of the story).
It's to do with the number of DIMM slots per channel used with a particular board. That is, Intel designed the memory controller with 3x channels, but it can have 3x DIMMs per channel, for a total of 9x DIMM slots. That's per CPU, so in a DP system, you can actually have up to 18x DIMM slots.
But the board designers have other issues to contend with, such as what is the board designed for, and how much physical real estate is available. So most boards don't have but 2x DIMM's per channel in the workstation range, and Apple's board has fewer than that (hybrid config of 1x DIMM on 2x channels, and 2x DIMM's on one channel - they're not the only ones that do this either, as Intel has a board that does as well).
Now I did the work for you, and found the memory configuration on Sun's Ultra line using Nehalem processors (35xx and 55xx), which covers both their SP/UP systems and DP systems as well (
here). Note that the RDIMM's work in the SP versions (Ultra 27 Workstation). It also applies to 36xx and 56xx parts as well, as the Westmere parts are the Tock part of the Tick-Tock cycle (Tock = die shrink, and maybe a few tweaks - the base architecture is Nehalem).
Could you name a few? Most of the search result was about the Mac Pro or some site that copied the Intel specs.
Most board specs do parrot Intel's data, as I noticed that the server and workstation boards stated 24GB of non-ECC memory, yet they're also meant to run the Xeon line (SP in particular), which is really weird. What's the point of stating non-ECC memory only?
I can only presume laziness, but there may be other reasons (don't know comes to mind if the author isn't one of the designers or didn't get the information from one
).
As per links that show RDIMM's can be used in SP LGA1366 systems, I found one that's linked above (read carefully, as it's buried in there with a lot of other good info). It's a blog from a Sun's site (expect this is either a knowledgeable support specialist or an engineer, as there's no detailed information as to the author John Nerl).
Another good link (offers clearer information as to what happens to memory bandwidth when using multiple DIMM's per channel) is from Dell (
here). It only refers to the DP systems, but is applicable to SP systems as well since they actually do use the same memory controller.
Well, Intel and specs on their website..sometimes specs seem to be living their own lives or something.
My instincts tell me it's a lack of communication and/or keeping the information updated with current parts availability (see the same with max capacities a lot with both systems and storage products). Even their board information only calls for 24GB of non-ECC in their SP/UP LGA1366 server/workstation boards.
And that's exactly the problem, there aren't any user reports about it working as such so we still don't know for sure. Which makes it a shame that OWC hasn't done some sort of follow up on their blog article. The article as it is now simply isn't that convincing.
Forget DigiLloyd. I actually trust OWC over his hardware information, and the link to Sun contains the details (they wouldn't claim support if it weren't true - not of the Sun I've dealt with anyway....), and further information that supports it is in the link from Dell (despite it's only referring the DP systems).
