Check your monitor manual to see if it's capable of running at 75Hz (most of the modern ones are). If the manual says it's able to run at 75Hz or higher, you can set it without any problems. Probably Windows is not detecting correctly your monitor's properties. If Windows does not allow you to change the refresh rate, just disable DDC. And if you can set it a bit higher, it's even better (85Hz, for example
).
Btw, your monitor is a CRT type, right? If you are using an LCD monitor, I don't think there is a need to set the refresh rate at high values.
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But there is someone who remembers you
Someone waiting for a sign that leads the way to you
There is someone who will die for you
Keep that in mind when the hope fails