Originally Posted by TheBirdman74
Just RMA it man, and tell them to test the new unit.before sending it to you. That's the video alright, I can see how the magnet fix can solve the problem but I rather RMA it, mainly because I'd probably have to leave the magnet there(which doesn't look very cool when you have a window) and even if I used a larger speaker type magnet to run over the thing a few times, it might just go back to its old grinding noises in a few months / year when the bearing goes out of place again. So I rather start off with a good unit. This time before you lap it, just test it with a spare PSU for an hr or so. Just to be sure.
edit: does lapping the concave finish really help much? how are you lapping it? I am guessing you could just do it with a small piece of sand paper and your fingers? or do you need a block? what grit paper are you finishing it off with, I think I only got 800 100 and 1500 at home.
Although I'd like to have a unit that works right from the start, I just hate the idea of waiting for the whole RMA process, lapping the 620 again, and re-attaching it to the gpu (with zipties). I just want to be done with it lol.
As far as the lapping goes, I haven't personally verified if or how much of a difference it makes. However, I did notice that the 620 definitely seemed to be a concave surface (as much as my eye could tell), so it made sense that I would want it to be flat. Especially since it's against the mirror-like surface of the die. But it may not actually make a huge difference; I didn't care enough to go through the trouble to do thes testing to find out.
I'll try to post the process that I followed to lap it. I found a better description of the process online than what is in the guide here. I didn't use my fingers (I did the first time) -- I used a piece of glass from a picture frame and moved the cooler head itself instead of moving the sandpaper. I'll post with more details later -- leaving work.
@Bogey1337 -- I'm assuming that you have your 620 hooked up to your CPU and so you put it under load to heat up the water in an effort to get rid of air bubbles. IMine is hooked up to my gtx470 (graphics card), and I used a gpu stress test (furmark) to do the same thing. I even intentionally unplugged the radiator's fan to let the temps get higher. Didn't really do much, because I think I have a bearing-related problem, and not an air bubble problem.Edited by lukeman3000 - 2/25/12 at 5:37pm