After receiving my RMA I have to give Silverstone credit for sending out a replacement very quickly. I believe they received my RMA last Tuesday and shipped the replacement out on Thursday.
I didn't have any noise issues with my first SX500, and hopefully the replacement will be the same.
I received my replacement SX500-LG from Silverstone last month after my original unit had problems with the power good wire.
My original didn't have the noise issue that many have complained about, but unfortunately I think my replacement does. It sounds a little bit like a mechanical hard drive, even though I have none. Given that the noise has only started since I installed the replacement PSU, and that it sounds like it's coming from the PSU, this must be the noise many have complained of.
Kudos to Silverstone for turning around my replacement so quickly, but I'm a little bummed to have received a replacement that has a separate issue.
To be honest, you could probably live with the noise. It's intermittent and not terribly annoying. However like many, I bought the SX500-LG over the model with the 80mm fan because I wanted it to be quieter. This pretty much defeats the point of buying a quiet power supply.