Use of Memory on G400 MAX

[Bendeigid]

I know this is maybe a stupid question but I have to ask it anyway.

The dualhead feature is supposed to use 16 MB of Video memory per monitor. According to Matrox when you use a single monitor output the card uses the full amount of video memory for displaying and gaming. However with or without dualhead it does not seem to make a lot of difference to the framerate.

Could somebody please clarify if the G400 series is really giving you access to the 32 MB VideoRam when used in singlehead mode or is it still reserving 16 mb per possible output?

TIA

[Maggi]

Howdy ...

Afaik, only the needed framebuffers will be substrcted from the total amount of gfx RAM, i.e. it depends on what resolution and colordepth you use on both monitors.

I never heard about splitting the mem into two 16MB chunks just by enabling the DH ...

Hope that helps,
Maggi

[Bendeigid]

I thought I have seen something about the splitting mentioned on Matrox own website but I can not remeber where. Might have been in one of the FAQ.

But your reply might explain why I do not see much of an impact when having Dualhead enabled and playing a game or using it in singlehead mode.

[TopCat[FCD]]

Yeah thats what I was always told.As far as I understand it ,the G400 DH enabled does split mem in two,in other words both outputs have ACCESS to 16mb but dont HAVE to use it all.

[Werdna]

I asked this question a long time ago under the name OzAndrew and I was told by the people here that you do end up with 16MB per monitor. You have to disable then restart to get it back to 32.

[Indiana]

Originally posted by Bendeigid:
However with or without dualhead it does not seem to make a lot of difference to the framerate.

Well, that's not that surprising: Ican quite easily match the fps numbers of the G400/32MB non-MAX that are posted here and on other places with my G400/16MB.
The performance-difference between 16MB and 32MB is not that big (as some marketing people would like to make you believe), in fact it's nearly unnoticeable for most games up to 1024x768x32 - and for higher resolutions the G400 is (IMHO) too slow anyways.
An example where you probably can see the spee difference is when you play QuakeIII in 1024x768x32 and turn the texture-details to max. My 16MB G400 gets very sluggish here, and I guess that's because of heavy swapping of texture from/to the AGP memory.