AMD Radeon HD 8970M 's Advantages
More VRAM (4GB vs 2GB)
Larger VRAM bandwidth (153.6GB/s vs 48.00GB/s)
768 additional rendering cores
AMD Radeon 540 Mobile 's Advantages
Released 5 years and 10 months late
Boost Clock has increased by 25% (1124MHz vs 900MHz)
Lower TDP (50W vs 100W)