Solved I5 2 8 4Gb 5750 Upgraded To I7 16Gb 6970 Stuttering Graphics Imac Intel 27 Emc 2390

Chosen Solution

Have you upgraded your OS (what OS are you using)? Have you upgraded the EFI? Both those come into play with the graphics change especially. Lots of free space on the boot volume? (15% of total drive size). Any or all could contribute to video performance issues. If this answer is acceptable please remember to return and mark it.