Power to heatbed

I've tested the motors connected to my RAMPS 1.4 and they work fine.
When I just connect the thermistors and attach the extruder (D10) and heatbed (D08) there seems to be no power getting to the whatsoever. I've tested it with a meter also and there seems to be nothing registering but the thermistor temperatures are registering in Pronterface. I'm currently using a 400w ATX to power the board.

Do I have to attach the motors and endstops to get a voltage reading for the D10 and D08 connectors or should I be getting one without them connected?

D10 (also D09 & the motors) are connected to the 5A input. If the motors are working, D10 (extruder) should also be working. Things to check are the config of your firmware. If it's marlin, make sure it's set to the correct board type - use 33 for RAMPS 1.4 boards.

D08 is connected to the 11A input. If you haven't connected the 11A input up, this would be why.

Also, D08, D09 and D10 should light up small LED's on the RAMPS board when they're activated (LED2, LED3 and LED4 respectively). This is (usually) a good indication if it's working or not.

Other stuff to check: You should have 12V (or whatever your PSU is putting out) on one side of D08, D09 and D10 all the time. It should be the side marked with a + (side nearest the power connector). The FET's on the RAMPS board switch/break the ground connection, so having the 12V there is normal.

Ah! I've just tried uploading the sprinter firmware and it seems to be working so I guess I'll stick with that for the time being. I've been having problems with marlin at the moment with RAMPS 1.4 so I guess I'm better off sticking with sprinter while I'm setting it up. Probably something silly I did when upgrading the firmware.
I've got it running on windoze 7 and pronterface so I'm going to see if I can get it going on Linux.
D'Oh I forgot to click on 'set' the second time in pronterface. That'll teach me.

Thanks for your help.