I think your 3DMark99 score is about right for G550.

AFAIK it has no Direct3D 7 features but like the G400 and G450 it has DirectX 7 compatible drivers (officially starting with Powerdesk 5.50). They are all Direct3D 6 level cards.

I think 6.82 has EMBM disabled on G550. I don't know if it works with other drivers though. I would try older.
https://ftp.matrox.com/pub/mga/archive/win_9x/

Powerdesk V. 6.82.016 for Win98 and WinME ----------------------------------------- Supported Products ------------------ G200 […]
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Powerdesk V. 6.82.016 for Win98 and WinME
-----------------------------------------

Supported Products
------------------
G200
G400
G450
G550

Description of release
----------------------
Supports Win98 and WinME only.
ICD included.
TurboGL not supported.

Main Fixes
----------
- Screen corruptions in sound forge
- Texture problems in Flight Sim 2002
- C++ runtime error in pdesk when switching languages
- resolutions are cut off when using 2 dfp's.
- Medal of Honor Allied Assault performance

Main known issues
-----------------
- EMBM is disabled with digital flat panels.(G550 only)
- smearing of web pages
- Using the G450 pci card on a system with onboard sound, audio will be degraded during
dvd playback if you disable the onboard sound and install any pci sound card.
- If you have selected 4 different desktop resolutions where all resolutions are in 32bpp
and one of the resolutions is above 1280x1024, your system may reboot when opening our
PC-VCR. We recommend that you put one of your desktop resolutions to 16bpp or lower one of
your desktop resolutions to below 1280x1024. (G200MMS with TV Tuner only).
- "Smearing texts" defects exhibited when scrolling with Wheel-mouse.
- Texture flashes in Serious Sam the 2nd Encounter.

There was a thread that explored the G550 pretty thoroughly just last year.
Exploring the performance of the Matrox G550

Thanks for the info.
So i decided to try a Matrox G400. Got about 4800 in 3DMark99.
Quite a bit more.

Then i upated its drivers from 5.4 to 6.8 because Ka-52 wasnt working.
Then i ran 3Dmark99 again, and right away i could see the FPS was lower, similar to the G550, and looked to me like Vsync was on. Refresh rate was 85, and the FPS maxed at 42.5, so exactly half.

I browsed around a bit online and downloaded powerstrip, and was able to remove the sync. Then the my score went up again to 4800.

So looks like the G550 was simply using vsync.

However i still was not able toget Expendable working without crashing after applying the matrox EMBM patch. Maybe i need a different retail version or something. Also the Matrox G400 tech demo boots up to the menu, but then never loads. No idea whats going on there.

On a side note, the bump mapping effects in Ka-52 are really nice, especially the water. There is also bump mapping on the helicopters and various other things. Game looks much better than on my GF2 Ultra (although there, i can play in Stereo 3D which is nice).

You can also tweak things like vsync and AGP settings with the Matrox Technical Support Tweak Utility. The MTSTU.

G400 has a more quality focused rendering pipeline than the Geforce cards so will look better. As long as there aren't visual bugs of course. Radeon cards are similar.

Have fun!

Good to know, the image quality did seem higher than the geforce.

Also didnt know about this utility, will give it a try.