finesthours, Welcome to Seven Forums. If you would, please fill out your system specs. I will help us greatly to be able to help you. In the bottom left of your last post you will see 'my system specs', click on that, there you will see another link update system specs. Fill it out as completely as possible and click save at the bottom. If you would like to see what we like, click my system specs in the bottom left of my post and see mine.
As for IRST, I don't know if you are running an Intel or AMD system. If you have an AMD chipset, you can't install it. If you are running an Intel chipset, you can. You are correct that it is Intel's Raid driver
. However, it contains a driver called, IaStor.sys. That is Intel's AHCI driver and you can only get it by installing IRST. On all my SSDs, I use it. It seems to perform better than Microsoft's MSAHCI AHCI driver. I assume you have your Sata controller in AHCI mode. By installing IRST, you do not have to run raid and you should notice no difference in the operation of your computer. It simply provides a driver to run raid if you decide you want to do so. If you have any further questions, don't hesitate to ask.
For your information, scannow is a system file checker which will verify system files and attempt to fix any that are missing or corrupted. Check Disk checks your hard drive for errors on the drive itself.