Video memory cache mode - UC vs USWC

[Kruse]

I found a rather undocumented option in the BIOS of my Asus P3B-F allowing "Video Memory Cache Mode" to be set to UC ot USWC.

Can anyone tell me the difference, and which of them is supported for the G400 Max?

UC is default. USWC is supposedly better, but it says to only choose it if the Video card supports it.

[Rags]

That option there is for write combining, it provides a nice little speed up if your video card and RAM are up to the task. The G400 works fine with it.

Rags

[Thundrchez]

If I'm not mistaken, Write Combining was originally introduced with the P6 bus on the Pentium Pro many moons ago. The Millennium I supported it way back then, and all Matrox cards have supported it since then.

[Kruse]

Thanks guys!

Wonder why that option isn't even documented on an otherwise well-documented motherboard like the Asus. I'll try switching it to USWC and see what happens :-)

[Gurm]

Basically it's not documented because only Matrox and ATI boards support it. ATI specifically tells you to turn it on in their printed documentation. I can't recall whether my G400 told me to in its print documentation, since I think I threw all that crap away along with the box. Hehe.

Anyway, the two stand for:

UC - (U)n(c)acheable
USWC - (U)n(c)acheable, (s)peculative (w)rite (c)ombining

It is the same thing that the old program "fastvid" used to do for high-end Pentium and all Pentium Pro motherboards.

- Gurm

------------------
Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.