Errr - cooling?
"Each processor consumes up to 65W, 90W for the whole server card, and 400W (TDP) for a full sled. A single rack can hold 48 sleds,"
That is a 20kW rack. Easy enough to assemble such a thing just using conventional blades but not that easy to keep the thermal issues under control. Last time I was involved in such a thing it required water or CO2 active rack cooling (TROX and KoolTherm are the names I recall) and it wasn't rated a success since the infrastructure required to support the cooling offset any space saving from the rack density - and that's before you factor in the extra facilities maintenance complexity and catastrophic consequences
of a coolant leak (insert Star Trek quote of choice)
Five or six years ago mind. Has there been some quiet revolution in this area recently? (and no, I don't count cold aisle containment).