Paul M. Cook wrote:

Dedicated video RAM is slower than DDR2 RAM as it uses the
restricted PCI bus speed

PCI video cards are long gone, it's years they're all on the north
bridge thanks to the AGP port.

Guess again. AGP is what is gone. PCIe is the new standard. AGP
died years ago. PICe is factors faster than AGP.

So why do you talk about "restricted PCI bus speed" ?
BTW: many of us are still using AGP, which is not dead, FYI.

Moreover:
1) the RAM mounted on video cards is way faster than the system RAM
and with a superior bandwidth

Nope. The bandwidth is identical.

Nope, and naver has:
As a GPU is extremely memory intensive, an integrated solution finds itself
competing for the already slow system RAM with the CPU as it has no
dedicated video memory. System RAM may be 2 GB/s to 12.8 GB/s, yet dedicated
GPUs enjoy between 10 GB/s and 160 GB/s of bandwidth depending on the model.
(from http://en.wikipedia.org/wiki/Graphics_processing_unit , search
"bandwidth" and you're right on the spot)

2) it is directly connected to the GPU so the GPU-to-video-memory
path is shorter, thus quicker

Nope. It is not. Shortness means nothing, speed means everything.

Shorter means "with less hops". If data has to flow between onboard video
RAM and GPU there's way less hops than from GPU to system memory via the
PCIe or AGP bus. Moreover the GPU is synchronized with onboard video RAM,
while it is not sync'ed to the system RAM, so many clock cycles will be
wasted waiting for synchronization of *every* data trasnission in both ways.
--
Vilco
Think pink, drink rose'