Smaller servers
I’m not sure I buy the hypothesis about a connection between small server rooms and small servers - small server rooms obviously have fewer servers, but there is no reason to suppose they are individually cheaper. If anything, I would expect them to come in *higher* on the IDC methodology:
First, it counts software sold with new servers, so a lot of small customers are going to be adding to it with things like Windows licences, where larger customers would be more likely to have a separate with software vendors, and more likely to have a significant Linux fleet.
Second, it counts parts sold with the server, so people who add memory/storage/etc separately are under-represented. That’s more likely to happen with mid-size or larger businesses, where the available savings are much larger and the benefits of standardisation greater.
Third, small environments are much more likely to use DAS, which means higher costs for a single server, and thus more in a higher bracket, rather than shared storage.
Related to the above, I would also say that small companies are far more likely to have been fully remote (hence in the category of not there to set it up), and to do most setup manually, whereas a bigger outfit would have maintained a minimally-staffed datacentre, and be able to automate (or at least remotely) do almost the entire setup after physically racking kit.
One thing which might well have skewed the market downwards is that 1S EPYC covers a lot of use cases previously in the 2S bracket, but the total platform cost is lower - and the stated AMD growth would be consistent with this.