First, have a look at the 2 MB variant:

Second, try the software from this CD - https://vogonsdrivers.com/getfile.php?fileid=939&menustate=0

Third, that card doesn't support 800 x 600 x 24-bpp.
1024 x 768 x 16-bpp, however, should work.

Don't worry about the different type of memory chips populated on the 2MB card. The SMD SOJ-40 chips are each equivalent to 4 of your DIP20 chips. The ET4000/W32i will not notice the difference between your 16-chip configuration and this 4-chip configuration.

One issue with a lot of graphics card at that time is the limited bandwidth of the interface between the video chip and the RAMDAC: It's just an 8-bit path, so it needs multiple cycles to transfer high-color or true-color pixels. A 800*600 true-color mode puts the same requirements on the ET4000/W32i chip than a 2400*600 256-color mode would. 1024 * 768 at 16bpp non-interlaced is just at the limit of what those cards typically support. A common observation is that upgrading cards of that generation from 1MB to 2MB only provides marginal benefits, especially if you can't use interlaced modes. In the specific case of the ET4000/W32i, you should get a notable performance improvement at 2MB, though, because 2MB allows the ET4000/W32i to operate in bank interleave mode, which provides a higher memory bandwidth, which is especially useful if the Windows accelleration function is used.

Thank you very much for the hints. I'll elaborate this when I'm back home today evening. When comparing the pictures I noticed an important difference. While the sticker on the ROM of my card says "v.8.00 HI, 1993", it says "1993 - 1995" on Grzyb's card. Screenshot dynpro4.png attached by Grzyb gives "8.0N-A2b (04/29/94)" as video BIOS version. This means, that his card has a newer BIOS than mine. Maybe the 2 MB upgrade also requires a new BIOS.

@Grzyb: Can you upload the BIOS of your card, please? If you don't have hardware for this you can read it out under DOS as described here:
Re: Diamond Speedstar 64 ISA BIOS rom needed

Here you are, see also the list of modes supported with 2 MB...

Topic resolved. Using the BIOS provided by Grzyb "Ver. 8.00N-A2b(04/29/94)" Navrátil recognizes 2 MB while it recognizes only 1 MB with my old BIOS "8.00N-H1z(10/29/93)". For the sake of completeness I'm attaching my old BIOS (maybe someone finds this thread later and wants to try it out).

The program DETECT.EXE does not produce any output under Windows 98, I'll try this later with Windows 3.11.

Thank you very much for the support!

Hirsch wrote on 2025-09-14, 15:19:

• I ordered Siemens HYB514256B-60 chips from China to upgrade the cards. They have the same pinout and specs as the original Mosel-Vitelic V53C104HP45 chips on the card. The only difference is, that the Siemens chips have 60ns while the Mosel-Vitelic have 45ns. ChatGPT told me, that 60ns should be sufficient for the ET4000/W32i.
• Replacing the original chips with the Siemens chips (just replace, not upgrading) works fine. I see no artifacts on Windows 98 on different resolutions. This tells me that I didn't buy fake chips and that ChatGPT didn't lie.

There's a 95% chance that they are relabeled 80ns chips, or 100ns if you're really unlucky - they will still work fine with most ISA cards and Tseng cards will tolerate 80ns fine, but you'll have issues if you're overclocking the ISA bus or MCLK speeds (if possible, ie. on Cirrus Logic GD542x cards).