Stack overflow hosts all (most?) Of their own baremetal servers in their own data center.

Looking at the specs of the machines, they are actually pretty basic as far as servers go. A server isn't barely worth the cost of it's chassis and motherboard if you put less than 64 G ram and 24 CPUs in it.

In other words, these are about the lowest specd proper servers you can get. So yeah, even their modest hardware is still overspecd for running their website.

"Their own data center" implies (to me at least) that they built their own data center. That doesn't sound right, so I looked it up, and it seems like they're colocating. That might be what you meant, but the data centers they use certainly weren't built or owned by SO.

As far as I can tell, you are correct. They manage their own metal servers/racks inside a colocated data center. Sorry if this caused confusion.

Yeah, I recall an article that said their physical hardware was in jeopardy during hurricane Sandy.

As CPU utilization goes up, latency will go up. Also, one or two second snapshots of CPU use are averages over time. During any given moment you will invariably get little bursts of requests, and those will have slow responses if running closer to full utilization.

Also, of course, the total cost per hour for 9 servers with 3 year depreciation is in cents.

Nick Craver went into that a bit here. https://nickcraver.com/blog/2013/11/22/what-it-takes-to-run-...

They have a lot more CPU than they need, but the challenge is often getting servers shaped appropriately (RAM x CPU x disk x network), especially if you're not building your own.

Ultimately, their service is (most likely) not compute-bound.

Yes but the overall hardware is a one-time purchase and cheap considering all the other costs of the business. They're well provisioned to keep latency down and handle any unexpected outages.