It depends on the application we are running and the amount of RAM we have in our system. Suppose our system has 8GB RAM, the iGPU would take 64 MB minimum and a maximum of 128MB for itself. This is a very small portion compared to the total size of the RAM. Intel Iris chips have a small amount of onboard eDRAM, either 64 or 128MB, that boosts performance. eDRAM is Embedded Dynamic Random Access Memory which is integrated along with the iGPU for its use. It is more costly than DRAMs but boosts the performance by a large amount. So nowadays we don’t have to worry about iGPUs consuming system resources too as it comes with their memory these days.