w8.1 - 64 bit

I've been running W8.1 - 64 bit on an Asus m3a78 motherboard for about 10 years with no problems. AMD processor. Up until now, my ISP provided me with "up to" 100 Mb - no problems there. I now have an "up to" 500 Mb fiber service. The wired speed tests all read around 80-90 Mb up and down, day...