OT: Radio Interference

I know this is quite a bit off-topic, but you guys seem to have pretty much all the answers here, and I am curious about something...

Last week I replaced the power supply in my home PC. When I powered up the PC, my radio immediately started buzzing. (AM radio, yeah, I know, I'm a ways away from satellite radio) It didn't do it with the old supply. Is it just a matter of quality, and how would I know what to look for if I replaced it again? Is there a way I can correct it?

Then this really threw me for a loop. I was at home last night cooking supper (listening to the AM radio again) and when I turned on an appliance, the radio started buzzing again. No big deal, that is pretty normal. What threw me was, when I turned on another appliance, the buzzing stopped. So as long as they were both running, or none running, the radio was OK. But with one appliance running...interference.

Most likely, it's not radio-frequency interference. It's probably power-line interference. You might try putting an RF Choke on the power cord of your radio(s) and/or the offending devices. It may or may not help, but it's easy and cheap to try.

Let's see.... Nebraska AM... must be KRVN or KFAB (I used to live in NE, too)

The PC supply is operating at 50 KHz. The AM noise is caused by a harmonic. Spend more on your PC supply. Look for one that is PFC. That should be a clean supply.
Each appliance is generating noise at the same frequency, but one is out of phase with the other. When both are on, the harmonics cancel.
There is a FCC rating on electronic appliances, but I don't know much about the details. I think it's a limit on how much noise you can radiate.
If the noise is on the power line, high end power strips should help. The cheap ones (less than $20.00) only have MOV's. I'm talking about the types that are $50.00 to $100.00.