Ok, we have been running half-life related servers for nearly five years so I am very familiar with them, but lately I have been completely stumped espically when it comes to scrds. No matter what our Source servers run like utter crap. Their FPS bottoms out once you have more then a dozen players in them. We are running a dual Xeon box with a gig of ram ,plenty of bandwith and so forth so I just cant see how its hardware related. At no point is the server tasking and yet it matters not whether their is one server running or four its the same story. Outside of the game servers their is a SQL server and Apache running and thats about it as far as major applications. I just cant seem to pin point the problem so any insight would be appreciated.

What are your tickrate and network rate settings?

Well the CSS and DODS servers are using their default tickrates at the moment so 33 and 66 respectively. Although, I have played with them a bit in the past but it made no difference. As far as network rates they are:
sv_minrate 5000
sv_maxrate 20000
sv_minupdaterate 15
sv_maxupdaterate 80


I have also moved these figures around with no real difference in performance.

mysql...?

yep

And your CPU and memory levels look fine? That's rather odd. Have you tried hitting the multimedia timer while running the server?

Sytem resource is not an issue and we are running a multiplier yet it still runs like crap. It never runs at a consistent rate. The server fps go from 300-10 all day long.