I just bought an open box Antec CP-1000 PSU and installed it in my system. I notice that there's a somewhat loud single CLICK or TICK sound every time it powers on or powers off. It's pretty much inaudible during regular operation. Is this normal for the CP-850/1000? I went over the SPCR review of the CP-850 and I can't find any mention of the click noise. I just want to make sure it's not defective because I have a fairly short return window. My previous PSU is a Corsair 520HX and it doesn't make that click noise, or if it does, it's really, really quiet.

My CP-850's did that as well, both the one I originally bought, as well as an RMA replacement. I'm thinking that it's normal.

Hi, my Antec Signature also does the same. A distinct mechanical sounding click at power on or off, almost like a relay. It's always done it and has no problems so far...

Regards, Seb

Thanks for the confirmation guys. At least now I know it's normal behavior. SebRad, yes, that's exactly what the sound reminded me of, the mechanical click of a relay. I just haven't heard it on a PSU until now. Like I mentioned, I was using a Corsair HX520 prior to this, and my brother has a Corsair TX650 in his box, and prior to that, I had a Seasonic SuperTornado 400, and he had whatever Antec 430W that came in the Sonata 2. None of these ever had this mechanical click.

It is a much higher power unit, so maybe it needs that relay, whereas the lower power units do not. My 530 W PSU doesn't click, but that sounds exactly like what my 800 VA UPS does when it cuts power to the "Eco" sockets (two sockets that turn off when "main" socket device turns off).

Good point, this is my first high power PSU. I originally wanted a CP-850 but found this open box CP-1000 for 20% cheaper than a new CP-850 so I couldn't resist. I'm going to add another XFX 6870 and cross-fire them, as well as pushing my 1090T past 4GHz so that's why I wanted a higher power PSU. The HX520 wouldn't cut it (it's also missing the 2nd pair of 6pin PCI-E connectors for the 2nd video card) for that kind of usage.

Now that you mention it, my APC 450W/750VA UPS does the same click when it cuts power to run it's periodic self-test. Speaking of which, I think I may have to upgrade my UPS to to match my new build/upgrade.