The plugins I listed above will simply remove the block that causes the servers to limit themselves to 64FPS on Windows machines.
In order for you to obtain anything above 500fps on a Windows machine your host/provider or server system must have some features enabled on it. Unless you specifically are hosting the machine, you do not have access to alter the needed configurations to obtain FPS that high.
If you paid for hosting from a reseller, you will need to discuss upgrading your servers FPS to a higher amount which may cost more.
If you are personally hosting the server, you can view the servers FPS by running it in a console and scrolling to the top. If I recall correctly, the server will not display anything over 500fps even if you have uncapped it to 1k+
You can also see your servers fps, which this should show things above 500, by using 'stats' command on the server.
There is a bios setting that needs to be altered and you may need to install a high-resolution timer patch depending on your OS version. I do not recall the bios setting off hand and I do not have the timer resolution patch on hand.
You should be able to find all the information you need over at:
http://www.srcds.com/