MikeSG wrote on 2025-04-30, 17:01:

DEAT wrote on 2025-04-30, 01:43:

There is almost no difference between a Trident 8900D and a GD5434/ET4000 W32i when it comes to WinG/DirectDraw performance at the same ISA speed [...]

By DirectDraw games I mean Starcraft & Diablo that use BitBLT in the actual game. On a CL-GD5429 those games are both a 5FPS slideshow. On a Chips 65545 & S3 928 they run borderline playable but not quite. This is at 640 x 480 x 8bit.

About video memory clock vs ISA bus clock.

Just tested overclocking the memory in a CL-GD5429 from 50Mhz to 80Mhz, 16Mhz ISA clock.

Starcraft: ~7FPS before. ~10FPS after. 10FPS is a screen full of busy units, roughly the same as the Chips 65545 and S3 928 did with 32-bit memory.

WinTach:
At 640 x 480 x 8-bit most of the performance stopped improving at 60Mhz, except Excel which was linear with memory clock.
At 640 x 480 x 16-bit, Excel scored a +34% improvement, which was more than the S3 928 did with VRAM.

It looks like with the 64-bit/interleaved 32-bit cards (1.5 - 2x faster at Starcraft) being memory-mapped over a larger video ram width, that data can be moved in larger chunks, therefore more is available to the chip. Higher memory clock is more for high colour/high-res applications.

How often drivers can pack what's needed into video ram is the other metric.