Question about CPU expandability in Mac Pro models

[ohkuipo]

Hi, I had a question about the design of a Mac Pro. Clearly, they're the choice for someone who'd like to upgrade their machine as time goes by. My question is, for the current design of the MP computers, how well does the logic board scale? Specifically, I was wondering if there were physical differences between the logic boards in MP models with one or two processors. Does the single-processor model contain an unused space for an additional processor, allowing it to be upgraded from 1x to 2x? Or is something like this just unheard of in the hardware world?

Furthermore, what future expandability does the community see for the Nehalem model of processors. Will the socket type continue to be used well into the foreseeable future (say, 4 or so years) by future processors? If I purchase a Mac workstation, I'd like to be sure of the details for what is arguably the most static element to their modular design--the CPU. Sorry if any of this is noob material, I'd just like to get my facts straight. Thanks!

 

[WytRaven]

The "logic board" is split into two pieces. 1 part houses the CPUs, RAM, and northbridge. This CPU module is different for quads and octos. There is no path to add a second processor if you start with a quad short of replacing the whole CPU module (no doubt an expensive proposition).

As fo acutally upgrading the CPUs the quads are the easiest as the CPUs have heat spreaders so a standard boxed xeon of the correct type could be installed with ease. On the octos you have what are known as "naked" xeons, those without heatspreaders, which are no harder to replace than the quads except that sourcing naked chips could prove difficult.

To deal with the naked situation you have two possible avenues. 1. Buy chips with spreaders and then grind them off (wet'n'dry sand paper is a common method and details can be found on any decent pc modding forum) obviously this involves a significant amount of risk. 2. Use chips with spreaders and rig up a thermally conductive spacer that fits between the heat sink and MOSFETS as installing chips with spreaders will break the physical interface between the heatsink and MOSFETS and they definately need to be effecetively cooled.

As for future proofing and socket life etc....that's anybody's guess in the end although intel roadmaps could be helpful as a general guide.

 

[nanofrog]

It can be done, but isn't such an easy proposition. Not to mention, expensive.

The logic board is actually the same, but the daughter board isn't. So you'd need to obtain the DP daughter board, and associate parts. Not really feasible, particularly with the cost of Apple replacement parts. The heat sinks are different, and aren't the same for each processor. Then you'd need flash the SMC, as that's different between SP and DP's.

As WytRaven mentioned, there is a difference with some of the processors. Some use the heatspreader (metal on top of the silicon die), others are missing it, and are hard to find. Removing it would be the most likely option, and it requires some skill, a perfectly flat surface, and a lot of patience.

The easiest option (sort of), would to be locate one that's gone up as DOA (parts sale only), and hope what you need is still functional. If it's local, and you can work with the seller, it might work out for you. But this would be a long wait I think.

Still interested?

 

[ohkuipo]

Thanks for the lengthy replies! It seems what I'm proposing is totally impractical and I should get the thought out of my head... I guess the common course of action is to stick it out with whatever processor your MP comes with. But, if I understand things correctly, it is somewhat common to buy a better processor somewhere down the line to replace your existing one?

 

[nanofrog]

But, if I understand things correctly, it is somewhat common to buy a better processor somewhere down the line to replace your existing one?

On PC's, it's fairly easy to do. Not so much on Mac Pros, as Apple tries diligently to make things difficult.

 

[Tesselator]

Thanks for the lengthy replies! It seems what I'm proposing is totally impractical and I should get the thought out of my head... I guess the common course of action is to stick it out with whatever processor your MP comes with. But, if I understand things correctly, it is somewhat common to buy a better processor somewhere down the line to replace your existing one?

The life of the socket as you were asking about is likely dead-ended with this current processor series. So there probably will not be a 12 core or a 16 core nor some other features offered at a later time like there was for the 2006 Mac Pros.

If you want to upgrade a 2009 MP from quad to octad you need to find and purchase a different daughter board.

If you want to upgrade the same processor to a faster version within the same series you just need the processor(s) and some patience.

 

[nanofrog]

The life of the socket as you were asking about is likely dead-ended with this current processor series. So there probably will not be a 12 core or a 16 core nor some other features offered at a later time like there was for the 2006 Mac Pros.

Actually, the LGA-1366 isn't dead.

1. The Core i7/W35xx parts don't use all the pins.
2. Nehalem is a Tock, so it's useable in the next Tick (die shrink).

Intel planned it this way.

It might even have a longer life still, if they can shift it to the low end desktop parts. That is, the replacement for the LGA-1156 used in the Core i5's, when the next gen (Tock) hits.

 

[Tesselator]

Actually, the LGA-1366 isn't dead.

1. The Core i7/W35xx parts don't use all the pins.
2. Nehalem is a Tock, so it's useable in the next Tick (die shrink).

Intel planned it this way.

It might even have a longer life still, if they can shift it to the low end desktop parts. That is, the replacement for the LGA-1156 used in the Core i5's, when the next gen (Tock) hits.

Oh that's good news! I figured it was dust this round. Kewlness!

 

[gugucom]

The need for a different daughter board should put a spanner in the wheels for most users though. Such proprietary parts are never available on an open market.

 

[nanofrog]

The need for a different daughter board should put a spanner in the wheels for most users though. Such proprietary parts are never available on an open market.

They actually are available, if you know where to go.

Macpalace is a good source for original Apple parts (new), but these are by no means inexpensive. Others as well, IIRC, but I'd imagine their pricing is very similar.

 

[Umbongo]

Rather than quoting I'll just summarize.

A 2009 single socket system may be able to move to a faster processor and/or one with more cores depending on whether the current system's firmware can support it. The 2006 Mac Pros do not support Harpertown or Wolfdale processors despite being the same socket and it being perfectly possible. You may be able to replace with a new 6 or 8 core processor in a few years for <$300, but I wouldn't count on it.

You should be able to replace the daughter board with a dual socket one, but you would also need two new processors and two heatsinks (I think two). At current retail prices you are looking at $3,000 to go from single socket to dual 2.66GHz quads. Maybe recover $500-700 or so from the sale of old parts as official Apple logic board repairs are expensive, so someone might pay a decent amount for a working board, but no guarantee on a quick sale.

With Mac Pros holding their purchase price so well it'll likely never make sense to upgrade these things at retail prices. Bare in mind prices don't really fall on Xeons and logic boards and the only way to do it on the cheap is to get lucky on processors, but there don't seem to be the bargains on 2008/2009 processors like there were for the 2006 quad cores.