Long read so here are some cliffs:
1. computer in trunk using m-atx power supply.
2. when computer on, radio reception crap.
3. tried adding grounds, removing wires, blocking interference possiblities.
4. used regular power supply with extension cord and radio is fine.
5. isoloated variables down to m1-atx power supply and cars electrical system.
6. very sad.

Ok, ever since I have had my car computer installed I have had really crappy radio reception. I don't use a radio capture card like a lot of people, what I have instead is a thing-a-ma-jig that plugs into my radio (stock OEM bose) that adds two aux inputs. this allows me to have lossless quality sound from my computer or other device to my head unit.

Ok, but really, only the really really strong stations come in and even then not 100%.

I thought for the longest time it was interferance with the lcd monitor in the dash with the radio. I built all kinds of shields etc. Then I thought it was the wires behind the dash so I wrapped foil around them and then 3 layers of electrical tape. Never made a difference. Then I thought it was dirty power to the LCD and the in dash DVD enclosure but after adding some filters to those, nothing changed.

I started thinking today that it was the cables running from the back of the car to the front (vga, usb(x2), rca, reversecam) but after unplugging them from the computer, nothing changed EXCEPT, when I unplugged the audio cable from the computer I had a momentary improvement of reception. So I thought it was a faulty aux input thing-a-ma-bob, but after removing it completely from the car, still no difference. It wasn't until I just unplugged the power source while the computer was still on and the radio was still on that it improved to almost 90%!!!

I thought "oh, maybe the computer is putting out signal interference!!" So I tested this by hooking the computer up to a standard power supply and running an extension cord out to the trunk. Powered up the computer and the reception was still at about 90% (which is good). Hmm, well maybe it is where I am grounding the m1-atx power supply.. so I ran a long ground wire from the battery, along side the car, and into the trunk. fired up the computer that way and the signal was back to 0%.

Still thinking it was just interference I took the whole computer up and sat it on my radiator support and used some extra wire and wired it up right there. When it booted, bam, still 0%.

This leads me to believe it has something to do with either the car's ground or power. I have tried grounding the computer case with little results. I just don't know what it could be other than the m1-atx power supply or the cars electrical system. Those are the only two variables left!!

So what am I doing wrong? Please help!! PLEASE!!

TIA

Mike

Edit: I have an M1-ATX PSU 90Watt