Corsair released a 2018 update of the RM850x power supply. This new update for the RM series now is offered in a silent RMx series that comes with 80plus Gold certification, that means it's 90% efficient at 50% load. Efficiency matters. The PSU itself is fully modular, for most of you with a side panel window in their chassis a must really as you'll want modular cables.
Slow computer got you down? Maybe a hardware upgrade should be in your cards, if so this guide to the Fundamentals of Upgrading a PC is an invaluable read. PCSTATS Tips