Just finished updating to El Capitan/Clover. Still haven't gotten my NVIDIA card to work but I had to use "Inject Intel" to get my HD4600 to be recognized. You can check if drivers are being loaded by going into About this Mac (under the apple menu at top left of screen). If loaded properly you could see "Intel HD Graphics 4600 1536 MB" listed under graphics. You can also check under system report by looking at the Graphics/Display section.