What is Fastwrite in AGP 3dCards? I should enable it or desable it?
Fastwrite is the only hardware data tranfer mode that isn't like any other hardware devices in your computer, it is the only hardware which didn't use the normal PCI/ISA BUS-MASTER convention with IRQ and DMA channels.
It is the only BUS-MASTER data transfer which didn't hog the system bus for itself as ALL Symmetric Processing devices ALWAYS DO. More Fastwrite details here.
If you have non-Intel, non-nVIDIA hardware then avoid turning on FASTWRITE. Without FASTWRITE then AGP is just a normal soup-up 66 MHz PCI bus device.