FirePro W5100 MemoryViewerC64.exe tool shows 100% GPU memory (4GB) in use & 0% available with no programs running. The CPU memory tab shows 11% used & 28GB available. Everything works fine however. As yet I haven't found a way to check if what that tool is saying is correct. MemoryViewerC64.exe came on the installation CD for the FirePro W5100.