[arch-general] Resume from suspend in RAM fails

Hello, Resume from suspend in RAM fails even though I have followed the Arch Wiki recommendations, with latest 3.12.7 kernel (and before). The 'resume' hook has been added for mkinitcpio and the machine goes to suspend from the command line (pm-suspend) with no GUI enabled. All keyboard and mouse lights are off and the screen is just black with no backlight. I can't even login through SSH and can't get any PM debug info. It happens on one particular machine only and I'm quite stuck with it. Any suggestions to solve this ? I can provide other relevent information if required. Thanks.