Did some googling with no progress. Just curious, anyone hear of a PSU, more specifically the one in my title having a low load squeal noise? It's not my fans, or my GPU. I know this because I stopped every fan one at a time and the noise is persistent. I know its not the GPU because when I run prime95 small FFT's the noise goes away. Same happens when I load up the GPU, the noise goes away. Basically whenever I put an average load on the PC it goes away. It only occurs when I'm idling and doing almost nothing like writing a word document (which is coincidently the worst time for it to squeal). As far as the noise goes, its a very very high frequency squeal that doesn't have much power. Although its still noticeable with a small fan running in the background. It just has this low volume piercing noise.
Its probably coil whine, the Seasonic X series have a problem with that, as you can see on reviews at Newegg. Call their office and have it RMA'ed.
I think I'll call them...too bad they don't post their hours. I sent three emails. Two Wednesday (different accounts as I heard they block certain domains), and one today. Yes with regards to the newegg reviews, although mostly on the 750, but I'm fairly certain these two PSU's are virtually identical. It's just disappointing when you spend $135 on a PSU and this happens. Should have gone with the XFX 750...although I think it too is made by Seasonic.