It's 4 CPU variations if you have purchasing agreements in place. If you're buying off the shelf from the vendors then yes it can vary much more. This is even evident in the desktop market. Compare the Dell business class to the Dell consumer class. The consumer class will change frequently, but in the business class you can buy 2 year old processors to match what you've got.

Yes you can buy 2 year old processors but then you leave 2 years of improvement/price falls on the table. Is a definable 70% performance better than a vague handwavy 100%? Depends on your use case but if predictability of performance (of a single host) is a priority you should be using a dedicated box.

My point was mostly that they sell other stuff but you have to go looking for it. The business class desktops are mostly for IT standards, so they don't have to update the image so frequently.

Making major purchases once a year and always getting the new stuff, you get 4 processors over the life of the hardware warranty (4 years, which I also believe is the timeframe for capital depreciation).

Purchasing 2x a year, you'll end up with 8 CPUs in the environment unless you opt for the 2H purchase to be the same as the 1H purchase.

If you're buying new hardware every quarter, those agreements become more important if you want to keep your environment homogenous.

If you're running thousands of servers, is it better to pay a premium on your hardware to be able to get the same machines for the entire year, or do you want to incremental improvements and environment fragmentation resulting from updating? Different models sometimes have different utilities to manage them, and now you're writing abstraction layers to handle mass updates.

I agree that predictability of performance requires dedicated hardware. I'm just going from the IT perspective.

for just cpu change, less than 300 but certainly more than 4. In just the 2 year from 2006-2008 before we exited to Rackspace we had more than a dozen cpu variants in production. We loaded the machines in a way where 'roughly' (with some hand-waving) things were the same for a given VM machine to machine, which allowed us to keep charging 20 bucks a month for the same instance regardless of which physical host it was on.