RobCrezz :
I just googled that model number and found another amazon link that said 4gb, but could be wrong!
Well,
this page near the bottom says that the 880M has 8. Lesser amounts are associated with different graphics processors. That makes sense.
Look towards the bottom under "Performance Graphics"
NVIDIA® GeForce® GTX 860M graphics with 2GB GDDR5
AMD Radeon™ R9 M290X with 4GB GDDR5
NVIDIA® GeForce® GTX 880M graphics with 8GB total GDDR5