I am a workstation user.

I've used both Mac Pro and HP Z800 workstations, and currently use a HP Z800 that is probably 3 or 4 years old, but also have used a Mac Pro as recently as 2 years ago.

I've never upgraded a CPU in a workstation.

The CPUs I buy are chosen for performance at a sane (relative) price. I'm currently running a couple of Xeon X5560 CPUs, I think they cost £1,600 each at the time.

I also buy as much RAM as is reasonable for the box, I started this Z800 on 24GB ECC RAM which was dirt cheap (relatively - as many slots on the motherboard meant I could get lots of the smaller sizes which were cheap). When the price later dropped on the larger modules I upped it to 192GB RAM.

As for graphics card... now that is something I upgrade every 2 years or so. I started on a Quadro FX1800 and am now on a Quadro 6000.

Aren't the names of these things wonderful? You know you get more when the number is HUGE!

I think this is basically the norm: Upgrade RAM, upgrade GPU... leave CPU until you replace the whole box.

PS: And whilst I'm here, the Mac Pro is a good design... but for the wrong product. I think this is a new design that is the right design with airflow, cooling and silence in mind and would suit desktop users well... but desktop requirements are not workstation requirements and not being able to replace GPUs is a non-starter. I'll skip this design of Mac Pro entirely, or at least until a very wide range of upgradeable GPUs are available. The RAM is also going to be costly, given the few slots available and the higher price for denser modules. I love the design, but this is the wrong class of computer for the constraints that come from the execution of that design.

It's a shame Maverics only supports 128GB RAM.

4 slots, 128GB max = 4 x 32GB modules @ ~£1k per module (price based on average observed price for 32GB ECC RAM).

£4k for 128GB RAM, compared to 12 * 16GB modules @ £200 = £2.4k for 192GB RAM.

Hmm. Yeah, I'll probably be sticking with the PC route and running Linux still.

Even with these purely speculative prices, the Mac Pro design forces fewer denser modules and is really going to hit the pocket hard.

Apple does not support CPU upgrades in the Mac Pros. You need non-standard tools to do it, it's not as easy as in a typical PC, and occasionally have to hack a firmware update depending on what Mac Pro model and what new CPU you want to use. The firmware hack is because Apple does not update firmware in older models to support newer CPUs, even though the hardware is otherwise capable of it.

I think people who upgrade their CPU in Mac Pros are a minority of Mac Pro users. I'm probably not a typical Mac Pro user (a "mid-range" tower would've been fine for me), but I bought a 2007 Mac Pro with the least expensive CPU option, then in 2012 upgraded the CPUs in it to extend it's life. The Xeon CPUs I used were ones Apple never offered, but they happen to work in the machine I had.

Also: I upgraded the graphics card several years ago, to an official Apple supported graphics (ATI 5770), but my Mac Pro model isn't officially supported by Apple (but it works fine). I also did a hack to get the current OS X version, Mountain Lion, running on my machine (it isn't supported by Apple). My Mac Pro borders on being a Hackintosh at this point.

What did you change to get Mountain Lion running?

I followed these instructions to install Mountain Lion on my 2007 Mac Pro 2,1: http://www.jabbawok.net/?p=47

Note: For a Mac Pro 1,1 (2006), you may also want to update to the 2,1 firmware depending on what CPU you are using (have to create an account and login on these forums to download the file): http://forum.netkas.org/index.php/topic,1094.0.html (The 1,1 and 2,1 are identical hardware except for firmware)

Xeons never shipped in sufficient volume to make up for the huge discount that the system assemblers like Apple, Dell, HP &c were getting; I remember looking at upgrading a ~2009 era MP CPU, and you couldn't get the fastest CPUs for significantly less money than just upgrading the entire box.

I could be wrong as I've been out of the powerful-beige-box world for quite a few years. However when I was in it, the upgrade and replace thing was always with consumer grade CPUs and was like this for everyone I knew. The xenon isn't really targeting the same market. Rock solid stability and sustained performance wasn't something the gaming crowd I was in was after. Massive over-clocks, super hot chips (that died hot deaths) and a GPU clocked to the threshold of showing artefacts. The frame rate must stay high at all costs. This is nothing like what the Xeon targets. Just a thought, and again, I may be wrong.

Not a Mac guy, but I believe the Mac Pro normally uses a Xeon chip, which I believe have used fairly stable sockets over the years. For example, socket 604 was used by the Xeon for 5 years, and LGA771 has been supported from 2006 to present.