LtG wrote:
Are you suggesting that a 32/64MB discrete video card will _always_ make the system perform _the best_? Compared to for example Intel's Iris Plus 650? Or even a slightly older HD 4400? You can check the benchmark score for those two integrated solutions vs your 512MB AGP card, which got better score? Of course your 512MB AGP is older, so it's not a fair comparison if age is considered.
AFAIK, the main issue is not with discrete VRAM, or RAM bandwidth. For 1080p you have approx 2Mpix, each taking 4B that's 8MiB for each frame, even with 100 fps that's "only" 0.800GiB/s, current bandwidths are around 20-40GiB/s.
If you implement the best video chipset as video that takes/shares memory from main system RAM, you will destroy its performance.
A video chipset will always be faster if it's implemented as dedicated video with its very own RAM when it needs to access RAM to refresh the whole display features at 30 FPS or more, and several Megabytes at that speed. At least RAM access between hardware devices is much faster than doing the same in software, but it still affects.
Integrated video cards that share main system RAM are not normal.
Most old PCI video cards had their own memory so they didn't need to make the main RAM controller chips busier. They were like dedicated video accelerated through implementing them with their own RAM.
Maybe that's why PCI cards without their own onboard RAM didn't work in some Pentium I motherboards. Probably they were made for systems that were able to share main RAM with the video. At the time those cards had less than 32 or 16MB, so it was common even for Trident VGAs.
So in those cases the system was as balanced and ran as fast as it already was capable of.
It is not normal that current dedicated video cards make look onboard RAM as a rarity and shared video as the norm when initially it wasn't so and when it's possible and more efficient to separate main RAM and video RAM buses for obviously more speed.
If you have a 2 GHz single-core CPU and a 400 MHz video card, in separate buses, obviously it would be as if you had added a Pentium I to your system just for faster video, but the moment you share main RAM for several things, the performance is cut down.
The RAM itself is slower than any CPU, so loading it with more accesses than just code execution and data access will affect the system noticeably by a human.
Don't forget that accessing video contents and displaying them at a speed that is perceivable by the human eye can block the execution a bit, but that's why people ends up looking for faster video and systems as soon as they run intensive multimedia applications that become laggy.
Even setting up CPU MTRRs to use write combine for video (write combine if I remember correctly, as in MenuetOS) results in noticeably faster video. So we can see that something as simple as 30 FPS video, or 60 Hz, etc., for the actual screen hardware, can affect everything when seen as an electronics system.
Remember that if your video looks slow, that huge slowing down will slow down all of your programs as well, and even more if they use the screen at all. One way to escape that would simply be to avoid using video at all, disable the display in hardware so that it shuts off, and execute most critical programs as if it was a headless machine... maybe that's why servers prefer to be headless, to cut down an unnecessary slow down for a display chip that it won't be running anyway.