Yes many are still avaliable, used or often even NOS. Just look for compatible chips on ebay, AliExpress and so on.

Are you talking VLB or PCI here?

VLB cards with 1MB and sockets for a second MB are quite common, cards with 2MB are uncommon, but 2MB with sockets for 2 more is exceedingly rare. If you know where they can be gotten affordably, let me know 😜

Also be aware that a lot of VLB chipsets can work with 2MB/4MB, but frequently are limited in the added value - many can only do obscure interlaced modes with the extra RAM, making it almost pointless.

If it's PCI, you hace more choice, but it's also easy to find 4MB cards, so not a huge point there. In general you can cannibalize other cards, ideally dead ones. Almost all expandable cards have the same DRAM chips, either 1Mb/128kB DIP or 4Mb/512kB SOJ package. Ensure the latency (the -x number at the end of the model string) is the same or lower than on the chips already on the card and you are good.

Vogons user Tiido recommended me utsource for additional memory chips for my ATI Mach64 CT.
It is usually much cheaper than ebay/aliExpress with tons of parts.

At first, i wanted to steal modules from ram sticks, but it was a silly idea (refresh issue)
(original topic : ATi Mach64 WinBoost - Memory expansion chips)

unless your running windows, probably not worth it. games and such dont use the memory, its really only for hires images. a 1024x768 16bit image is 1.5mb..
and doing games that need vesa 800x600 or something on a 486 is probably not a good idea either 😀

acl wrote on 2023-01-26, 15:18:

Vogons user Tiido recommended me utsource for additional memory chips for my ATI Mach64 CT.

I keep my fingers crossed that you can actually get a decent amount of chips for the price listed on the web page. You might need it. Furthermore, utsource has a considerable order fee for "low-volume" orders, so just ordering 8 chips at utsource is quite expensive, even if you can get the chips at a low item price.