Well the simple answer to your question is no. There is no 'Hard disk limiter' function in windows. Programs though like virus scanners and malware usually have a setting to only use so much resources. Its sometimes hard to tell what program is ' causing' your 50% usage. Though things that come to mind are virus scanners running in the back ground / malware / system restore points / Indexing. These tend to be the usual culprit of 50% disk usage. You can look in your task manager and usually nail it down to a program or process by looking at resource monitor. This below excerpt taken from here. It could even be indication of a failing hard drive as it is trying to write and re write bad clusters.
What's Got the Disk? Monitor Disk Activity
The Disk section, as you probably know, shows you what's using hard drive resources. This can be very useful if your hard drive light stays on and you're not sure why. There are three windows labeled Processes with Disk Activity, Disk Activity, and Storage. Expand them all and take a look. You'll probably also want to expand the column headings so you can see the whole title. In the column headings, "B/sec" stands for "bytes per second."
There is not a lot you can (or should) do with the information in this section. You might be surprised to see how much disk activity your favorite programs require, but again, since Windows programs are usually well behaved, it would be very uncommon for you to see something really going crazy and making your hard drive keep churning away, except for programs used to download files. As with the other Resource Monitor sections, you can right-click on any name you don't know, and click Search online to get an explanation (this works in the Processes with Disk Activity section only). You can also end those processes from the same right-click menu, but again, that's not recommended unless you know what you are doing. In the Disk Activity section, right-clicking on the names does nothing, so if you're curious about those, you'll have to look them up on your own.
The bottom section, Storage, shows a list of your drives with information on Logical Disk, Physical Disk, Active Time, Available Space, Total Space and Disk Queue Length.
The first few are self-explanatory. "Disk Queue Length" is an indication of how many requests for disk space are waiting to be fulfilled. Unless you're doing something out of the ordinary or you have software that's seriously misbehaving, this column's data will be mostly zeroes. Which is as it should be.
Edited by YeahBleeping, 25 March 2015 - 10:24 PM.