Cooling, backup, RAID, graphics interface, I am not missing this discussion these were topics over lunch at work...so here is my 2 cents-
Air cooling except for the really hot processors is still okay, even for majority of large servers they still rely on air cool, but now they have refrigerated modules with pipings to cool the inflow air per rack. Others relocate the racks to group highly utilized servers with those low densities or utilizations.
Make sure you do regular back up, many are already relying on cloud services buying backups services for example in my case if I wanted from smugmug, I backup in external Gdrives. Now if your data are critical rotate your back ups keeping one in another location, say at work to backup your home files. I also back up in CD some family photos, use korai, smugmug and photo bucket to store too.
RAID redundant array of inexpensive disk, was a way to ensure high availability of not loosing data before you backup, the other way is to mirror your files in expensive drives, many large mainframe users have GDPS, globally disperse parallel processing, so two or more of systems say in NY, Bethesda, Colorado and Seattle will be running hot with data mirroring and instant recovery ready to take over when one fails. Do we need this at home?
Outboard processors like graphics are important and can boost performance and worth every penny.