Image via WikipediaWell, the servers we bought (Dell R200) were in fact very cheap.
We were using 2 of them and they could not stack up to 4-5 year old servers (Dell 1750 and 1850) which have SCSI hard disks.
I added a 4 year old Dell 1850 with SCSI disks next to the 2 R200's which were all connected to a separate server running pound load balancer. The total number of maximum concurrent connections tripled.
The Dell R200's cannot actually take SCSI/SAS drives (unless you go buy a proper controller). By default, they can only take Nearline-SAS which I heard is not something you would want for a web server.
I would have to say that I am putting the blame on the SATA drives. I would have thought that by now, SATA drives would be as fast as old SCSI drives, but I guess not.
Apart from that, I am still surprised that the new R200's with EIGHT Gbs of ram could not keep up (not even close) with much older servers.
What I'm looking into now is using squid for web accelerating. There is a good article explaining how to install it.
While I can plainly see that the servers we chose were not amazingly fast out of the box, I'd like to believe with some tweaking and using more of the memory, they could get close to the older servers.
The final point is, that it costs man-hours to do any tweaking to the new servers. If you calculate the cost of the man-hours you would be better off just buying a faster server.