Originally Posted by markrubin
looks like the OP used a cheater plug which lifts the AC ground
the most common cause of such noise is the cable TV feed: it is usually at a different ground potential than your house ground, hence the hum: if you have cable TV service, try disconnecting the cable feed: if this fixes the issue install a ground loop isolator (cheap Radio Shack part or your cable company may give you one)
Hmm, I dont have cable television or anything like that. Only HDMI sources. HTPC, and Bluray players.
Here is the odd thing, I disconnected everything and only had the one HDMI going from the PC to the Marantz 7702 and the noise was still there, I even tried outputting from the 7702 to another power amp (I have two), different power lead, different HDMI cable, different HDMI input ports on the Marantz, different ports on the PC (HDMI, DP), and also tried different power sockets including trying the same power board the amps live on... real head scratcher.
It only shows up when the GPU is under load, kind of a fast ticking noise. I also tried my old video card. GTX 1080 right now, GTX 970 before that. Both have the noise. The only thing I havent tried is a new PC powersupply but I highly doubt its that. Its a very good Corsair 1000w PSU. I also tried completely disconnecting everything from the PC, aux audio, keyboards, everything but the HDMI.
Muting the amp makes no difference, changing the amp input away from the HDMI input still retains the sound... very odd. The sound is much louder when there is no Projector display plugged in to the amp, and goes a little quieter when the projector is plugged in. That's odd too.
Kinda sounds like I need to ground my Marantz properly some how, that amp only has a two prong power lead. May explain why some of the noise went away when I plugged in the JVC Projector which has a 3 prong lead.
Odd thing is its ONLY when the computer is under any kind of load... I use MadVR so only really when that is running a film does this noise occur. I could listen to music all day and its perfect, watching movies without MadVR is perfect too...
Running games also produces this noise before you say it could be MadVR....