Update your post to include full system hardware specs and OS information.
Include:
Motherboard
PSU
Drives
Other components
The guiding document is the motherboard's specs. The User Guide/Manual may help also.
I was able to find this:
http://www.findlaptopdriver.com/pegatron-memphis-s-mainboard-specs-7252012h79/
[Do verify that I found the applicable specs.)
The motherboard must support the GPU and the PSU must have the quality and wattage to support the host system and GPU.
Is there a date or version number anywhere on the motherboard?