Plastic Washer: M3 6mmx3mmx1mm. Total of 10 washers used for all the backplate screws that mount the entire HS. 4 of them were used for the GPU bracket. I unscrewed 2 screws on the same side of the bracket 1st. Then inserted the washer. This made it easier for me to put the screw back into the hole without having to hold down the bracket Once all of them were on I made 4 turns each then 2 turns the 1 and 1 (something like that) catty corner. Temps: I am seeing 4-5C drop in HotSpot Temps vs without Vregs stay 50C or lower. Before around 52C-54C Ambient temps up by 2-3C. Now the fan stays at zero on boot up. Temps have to creep well past 35C but I didn't wait that long to turn the fans on. So, yeah, it's working. But I put washers on all the backplate screws not just for GPU. That's why I'm seeing nice improvements on the vreg temps as well. It's fairly easy to do. Finding the right M3 washer was time consuming.