Dual Socket Server Boards - Can A Single Core Access All Memory?

[Lupius]

My workplace is interested in building a workstation for large-memory applications. I've looked at dual socket boards which support up to 64 GB memory, but CPU specs usually list that they can support only up to 32 GB. Does this mean that the 64 GB is split between the two sockets? If I were to run a single-threaded application, would it be able to access all 64 GB of memory?

[hexophrenic]

No.

[Lupius]

but CPU specs usually list that they can support only up to 32 GB

This part is actually not true. I was looking at desktop CPUs. Server CPUs can support up to a crap load of RAM. So... can a single core access all RAM on a dual socket board?

[digip]

I don't think it has to do with number of sockets, but the underlying chip architecture and OS in place as well as the hardware its put in. There are plenty of servers with more than 64GB of ram. I know the game server I have in my steam favs is a dual quad core with 48GB of ram, so guess you have to do some more research on the whole package, and not just individual components, but putting them all together. If the OS you use has a limit, don't spend the money on the hardware if it can't be used, and vice versa.

http://msdn.microsoft.com/en-us/library/aa366778(v=vs.85).aspx

http://www.cyberciti.biz/tips/maximum-memory-and-cpu-limitations-for-linux-server.html

[zanginator]

Quick anwser is No

The cores dont usually share memory as they'd end up writting over each others temporary files.

Its best to think of these boards as 2 seperate pcs on one board (or a cluster)

[Lupius]

Taken from wikipedia:

Earlier SMP systems used motherboards that have two or more CPU sockets. More recently[update], microprocessor manufacturers introduced CPU devices with two or more processors in one device, for example, the POWER, UltraSPARC, Opteron, Athlon, Core 2, and Xeon all have multi-core variants. Athlon and Core 2 Duo multiprocessors are socket-compatible with uniprocessor variants, so an expensive dual socket motherboard is no longer needed to implement an entry-level SMP machine. It should also be noted that dual socket Opteron designs are technically ccNUMA designs, though they can be programmed as SMP for a slight loss in performance..

So it's really up to the programmer to allow the process access all memory then?

[digip]

Taken from wikipedia:

So it's really up to the programmer to allow the process access all memory then?

Well, the programmer, and the OS limitations in combination with hardware limits. Again, depends on the whole package as a whole, while one part of the puzzle could use more, another part might be limited, so know what to buy before building so you don't end up with extra memory you cant use, etc.

[digip]

Quick anwser is No

The cores dont usually share memory as they'd end up writting over each others temporary files.

Its best to think of these boards as 2 seperate pcs on one board (or a cluster)

That doesn't sound right. You aren't running two OS's on a single box at the same time natively(other than with virtual machines). I've got a 6 core machine, and its not considered a cluster of 6 machines because of this. Doesn't matter how many sockets it has either, its still one system controlled by one main OS.

[CrYpTiC]

No.

BIOS wont let the single CPU take both banks. There's no way around it. It's rare to find a duel socket mobo that will allow you to do it.