Two power supplies
I've tested the power draw on my pc (M1-ATX, M10000) and when its running on its own its pulling about 3.2A onto the M1.
When I put it into standby, its pulling about 0.18A onto the M1, and when I pull all the external USB devices, this drops down to 0.1A in standby.
Now, 0.1A isn't a heck of a lot and with a 90AH battery in a car that gets used every day (longest period unused is 40 hours at the weekend - it "should" last 900 hours at 0.1A), I reckon I can put it into stanby and not have any real battery issues. This wouldgive me very rapid start times, without the hibernation issues (current best return from hibernation is a paltry 40s). For holiday periods I can always hibernate it/turn it off.
Installing this in my car is not an issue per se, but running power to all of the peripherals - touchscreen, USB hub, external audio card, USB TV, bluetooth , external HD (NEO jukebox with all my MP3s on) from the existing M1 will overpower it.
I want to have stabilised voltages to all the bits, so I'm considering getting EITHER
an M2-ATX to replace the existing M1 and then tapping all the power supplies into the PC, but this would increase the standby current draw to 2 or 3x what it could be.
Using an "external" M2 to drive all the peripherals is a neat solution as far as I can see, as I can set a "power off" delay and it'll give me enough amps at +12v to drive the screen,the NEO jukebox HD and possibly the radio tuner as well
The neatest thing I thought of though is being able to cut the power supply to the external USB devices, which, although some of them have their own external +5V supply, they do draw power down the USB cables when the PC is in standby. So, by tapping into the USB +5V lead from the PC to the USB hub and using a relay to disconnect that when the IGN is off, I should be able to get back to the 0.1A current that the M10000 needs in standby.
Are there any reasons why this wouldn't work?
sounds like it should work.. and if it doesnt its easy enough to reverse your changes...
I say go for it
Just order a 5V POL from the store to power your usb devices by the POL instead of buying a complete PSU.