Do this from within Windows, i assume Windows 7:
System and Security
Inside the Power Options You have to select a Power Plan: Balance, Power Saver or High Performance. If you don't see High Performance click on: Show additional plans, THEN SELECT HIGH PERFORMANCE.
This is all there is to it, nothing more. It does not matter if is a pc or laptop. If you can register to a forum i believe you can find this as easy. That is all the help i can give you but you have to help yourself. If you insist of going into the Bios setup, check for a frecuency multiplier or bus freq. multiplier. If in doubt set all to defaults and restart pc. bye
This message was posted on behalf of Intel Corporation
Thank you for contacting the Intel community.
Please bear in mind that your best contact support is with your system manufacturer as they are more familiar with your system and how all the components interact with each other.
In this case, you will need to check with your computer manufacturer where in the BIOS you can set up the system to run at 2.80 GHz; however, this could be a limitation from your system manufacturer and perhaps with BIOS update can work better.
Now, I don’t think this is making your system slow, what’s making your system slow it could be something else, try updating all your drivers and make sure you are using an operating system compatible with your system. Make sure you are using Windows® 7 with this system, if you have Windows® 10 installed, issues like this can occur since this system is not compatible with Windows® 10.