I have ESXi running on an old cast off desktop machine. It's running a quad core AMD Phenomn 9850 Black edition cpu, 4 gig of DDR2 ram, and an SSD for the data store. The guest operating systems are LAMP servers hosting about a dozen sites. For the most part it runs just fine, until a site decides to run a backup or beat up on its database. Then everything, on every guest VM, starts crawling. Looking at the ESX performance charts the CPU is the bottle neck. When it hits about 50% utilization everything slows down.
So, its upgrade time. I've budgeted $400 - $500 for the CPU and I'm faced with a choice. Which gives me more performance for running files compressions, database look-ups/changes, and web hosting a single more expensive 6 core Xeon or two less expensive quad core Xeons? (looking at Newegg 6 core Xeons start at around $500, give or take)
A second related question, can you run a single processor on a 2 processor mother board.
(finally a clarification. This is a server that will be mounted in a rack. It will be asked to run 24x7x365 without a glitch or hiccup while serving up web pages, accessing databases used by those sites and running compression on the backups. It will never, ever, never be a gaming machine, used to render videos, heck it won't even have a monitor attached.)