I just bought a 128gb ssd. I want to do a fresh install of 8.1 & for now just have the os on it. My OEM Win HP Pavililion P6-2326s came with Win 8. I upgraded it about 5 yrs ago to 8.1. Can I use an 8.1 iso with the existing oem product key since it has been upgraded or do I need to use an 8 iso & then go through the upgrade process again? I plan on keeping the other hdd's in service, this is just a speed boost change. I'm open to any suggestions about better performance.