On 10/5/2014 6:17 AM, Valeri Galtsev wrote: > John, I would respectfully disagree. The bad thing about "shared" memory > video cards is fundamental in the architecture. They use as video RAM a > portion of main RAM, that means they place the video traffic (30, or 60, > 50 25 frames per second multiplied by number of pixels worth) onto memory > bus. This traffic has nothing to do with anything but the screen and just > doesn't belong there. It is logically independent on anything and should > be kept separate from memory bus - physically. > > I mentioned single board computer I soldered for my kid back then based on > Z80 processor as an example of how rudimentary is to mix video traffic > into memory bus. It was OK to do that on trivial amateurish single board > computer. It is awful to step that low from architecturally good dedicated > video ram away on modern sophisticated computer. My computer science > degree rejects that and asks to take from "inventors" of that away their > computer science degrees. the Z80 had maybe 2MB/sec of memory bandwidth (thats off the top of my head before coffee). A Z80 system rarely had over 64K of ram, usually static, btw.. the DDR3 on a Intel i5-4570 (random upper midrange cpu I picked) has 25.6GB/sec memory bandwidth. a typical 1920x1080 display is 2Mpixels, at 24 bit/pixel and 60Hz LCD refresh rate, thats 360MB/sec to refresh the display. almost *nothing* compared with that 25GB/sec bandwidth. lost in the noise (half of the .6, to be more specific). -- john r pierce 37N 122W somewhere on the middle of the left coast