[AnthonyMouse]

It's not even the reliability which is the issue. Newer servers can put hundreds of cores in one physical machine, while taking up the same amount of rack space and using the same amount of electricity as older systems with tens of cores.

How long do you want to run something that uses 3x the electricity for the same level of performance when you're buying power by the megawatt? How about the even older ones that use 10x as much?

[mpyne]

Yes that's a thing too, but it's a question of cost and potential revenue. So if replacement hardware is really expensive then maybe you make the inefficient stuff hang out longer, as long as it's not broken and you have paying customers.

But at some point hardware does break and if you're going to keep the datacenter open for business you'll need to address turnover of inventory on an ongoing basis, and if you haven't locked in long-term deals for hardware then you'll have to bear current market prices when you do that.

[AnthonyMouse]

I would suspect that "hardware breaks over time" is a minor component of the cost. If you put computer hardware in a climate controlled environment with conditioned power, generally >90% of it will still be operational after a decade, with the expected replacement of wear items like fans and drives. To the point that the fraction of older hardware that fails will typically be smaller than the fraction you would replace for efficiency reasons regardless, and wouldn't be a large proportion of operating costs even if it wasn't.

Exceptions naturally if you for some reason had an abnormally high failure rate, e.g. capacitor plague.