So now that I finally have my setup working as quietly as possible with proper fan control, I have discovered a noise previously masked by the too-high fan RPMs / B12 drone issue. Namely, my Corsair AX650 has a buzzing noise.

This is a problem because although it is soft, it is distinctive, irritating, and still audible at sitting distance — when no other sound is present in the room, that is. I specifically chose this model over the Silverstone Gold Evo 750 (with short cable kit) because of its "pseudo-fanless" quality (fan doesn't turn on until high load). It was a pain cramming all those cables in my mATX Silverstone FT03, but I kept telling myself it would be worth it for the low noise.

This puts me in a little bit of a quandary. First of all, is this normal for the AX650? Does anyone have an AX650 which is actually silent at low draw, or are all PSUs expected to create at least a little buzzing (that is normally inaudible over typical "loud PCs")? Would you recommend that I RMA it? If I RMA it, will Corsair actually check the replacement before sending it out to make sure it is silent? When RMAing a PSU, do you typically have to send the whole thing with cables back, or can I just send the PSU (if I have to take out all my cables, then fugeddaboudit! )? Finally, does anyone have an alternate recommendation?

Thanks for your input guys,
—G

I don't know about the AX, but as it is based on Seasonics, and I've had two buzzing Seasonics (S12s), I would wager it's working as intended. You can try an RMA, but after buying my second audibly buzzing unit, I just sold it and got a Corsair HX (which I'm not sure if it buzzed, actually, but it was not audible at my sitting distance). I would switch brands, maybe try an Enermax or Kingwin or Nexus?

Corsair has been good to me about RMAs and service, but I don't think they'll check the noise a replacement makes, just that it is technically working. If you RMA, they probably just want the core unit (I've RMA'd PSUs, HDDs and motherboards, always just the core unit).

PS. What do you need such wattage for? More wattage, more components, more problems...

It's not so much the wattage, as the premium components. I like the PSU to be rock solid. Also, as I was going for as quiet as I could without actually going fanless, the Seasonic X-650/660 and Corsair AX650 looked good (both are the lowest wattage in their model range and have pseudo-fanless operation).

Although, truth be told I don't mind being a little overkill on the wattage.

I'll call Corsair on Monday and talk to them directly, see if they can check a replacement unit for silence before they send it.

EDIT: Called, and as I kind of expected, they really couldn't answer whether it was normal without hearing for themselves. In the tech support rep's words, "I mean... all PSUs make a little noise, but inside a case with the side panel on it shouldn't be audible. It shouldn't be audible unless you put your ear up to it, not over the other components." I explained that I was making a quiet PC, so my other components definitely didn't make enough noise to mask the PSU noise I was hearing, but understood that there was no way for him to know if it was in spec or not without hearing it for himself.

I am going to request an advance RMA with the intention of returning whichever of the two is quieter. That's the best solution I think.

EDIT: they didn't have an AX650 on hand so they are very nicely sending an AX750 at no charge. I will compare the two and send back whichever is quietest, or keep the 750 as a consolation prize if both buzz. Either way, solid support from Corsair. I just hope I'm not wasting both their and my time over this issue!

I would be interested in hearing what you think about the replacement AX750 they sent you. I have had an AX750 for about a year, and the coil whine that it has developed has become quite aggravating. It was always there from the very beginning but was quite faint and easy to ignore, and I was hoping it would go away eventually. Now it is so piercing and shrill that it cuts though everything, including headphones. It's not even very loud, just insidious.

Perfunctory Googling shows that the AX line does seem to have this problem. Personally, I don't think any kind of "buzz" or coil whine is normal or acceptable, and I too am thinking about switching brands.

First day with the AX750. Been keeping an... ear... on it while I do normal computing, benchmarking, games, etc.

This unit also buzzes. But so far it's less often and significantly quieter than the AX650, to the point that I cannot hear it at normal distance (~5 ft from PSU) with fans at minimum. To hear the buzzing over my ~400 RPM noiseblockers & ASUS GTX 670 at idle I have to get my ear within roughly ~3 ft of the PSU, and even then it's not as noticeable. This is only when I deliberately listen for it, as well, which is a big improvement over the AX650's soft but inescapable intrusion.

I'll keep the unit in my build for a few days and see what shakes out. If all goes well, this is as "bad" (which is to say, it's pretty good) as this unit will get.

Thanks for the update. What you are describing sounds pretty much like what my AX750 was like out of the box. I hope that you have better luck than I did and that your unit does not become louder over time. It took mine months to get to a level where it became easily noticeable and then months more after that before it became intrusive.

Was the RMA process pretty smooth? I think I am going to RMA mine but look for a permanent replacement just the same.

Did your unit begin with coil whine? Because neither my 650 nor this 750 have any, at least not that I've heard. What I have sounds more like "zzzzzzzzz" albeit very softly.

I too am hoping that this represents the worst of it and it won't get worse over time. As it is the 750 is totally fine to me, whereas the 650 crossed the (admittedly stringent) line.

The RMA is going totally fine. I haven't sent back the other unit yet but I don't anticipate any problems. Corsair's support has been very good.

Yes, I suspect it did. But it was incredibly quiet, just as you describe - an extremely, extremely faint "zzzz" sound; it was so quiet that I could only hear it if I pressed my ear to the back of the PSU. I couldn't even hear it if I stood up.

I convinced myself that I was imagining things. The sound was never consistent; maybe I would hear it every third or fifth cold boot, and then only for maybe 10 seconds right at the very beginning of everything getting warmed up. By the time the computer was operational, the noise was gone and I would have forgotten about it. It was only after months that the noise both got louder and lasted longer that I realized in retrospect that I'd been hearing something from the very start.

Frankly, I wouldn't have even been suspicious except that I have an old trusty 330w Seasonic unit that, after four years of hard wear and tear, makes zero noise whatsoever - no whooshing, no "zzzz", nothing. The AX750 was my first higher wattage PSU so I sort of told myself that maybe a faint trace of noise was to be expected from a more powerful unit. I no longer think this is true, lol.

Not to ramble on about my own stroke of bad luck or to scare you, of course. Hopefully yours will hold steady!

Good to hear that Corsair support is on the ball. I will contact them this weekend and see what they say about my situation.