I have a Sager NP8651 (rebranded Clevo P650SE) with a GTX970M. I’m currently running 64-bit Arch Linux with the latest kernel and the 352.21 drivers, but I’ve reproduced this error in the last two versions of Ubuntu and every nvidia driver release and kernel release since December.
What seems to be happening is that during standby (suspend to RAM), the GPU is not powering down properly. The computer gets very warm over the GPU (warmer than during operation, as the fan has turned off), and the battery drains completely in about 8 hours. The battery is fine, and will operate for the normal 4-ish hours when the computer is powered up as normal.
I have seen other people report similar issues. An example: https://unix.stackexchange.com/questions/213962/huge-battery-drain-during-suspend-to-ram-12-hour-nvidia-card-doesnt-turn-o