Both offers you found seem to be the correct type of chip (256k x 4 FPM DRAM), which is good. But they are considerably slower than the chips that are already mounted on the main board. The first ones have a RAS access time of 60ns, and the second one of 100ns, while the chips on the board have 45ns access time. The 60ns chips might work if the ET4000 is using conservative timings (but why would Dell use these ultra-fast chips then?), but the 100ns chips are definitely too slow.

Thank you for the reply, I didnt pay attention the speed of the chips on the board, but that makes sense. It seems finding the 45ns 20dip chips is harder than I thought.

It seems like these should work based on the specs given

https://www.utsource.net/itm/p/213590.html

camry_dude wrote on 2023-11-09, 22:41:

Thank you for the reply, I didnt pay attention the speed of the chips on the board, but that makes sense. It seems finding the 45ns 20dip chips is harder than I thought.

It seems like these should work based on the specs given

https://www.utsource.net/itm/p/213590.html

Yes, that should work as it is the equivalent in DIP format of the ones that are soldered to your board.

camry_dude wrote on 2023-11-09, 22:41:

Thank you for the reply, I didnt pay attention the speed of the chips on the board, but that makes sense. It seems finding the 45ns 20dip chips is harder than I thought.

It seems like these should work based on the specs given

https://www.utsource.net/itm/p/213590.html

Yeah, these chips will match. Most 50ns chips likely will work fine, too. Finding 50ns chips might be slightly easier than 45ns chips - but the key issue is that DIP chips were considered mostly obsolete when DRAM technology achieved speeds better than 60ns, so these chips never were a high-volume mass-market product (and don't blindly trust the "stock amount" given on that website. You will know what they actually have in stock when you placed an order. I experienced that they might try re-negotiate price and order quantity after I already paid using PayPal, which is in-line with other reviews of that shop). Most graphics cards at that time used a single SOJ-40 socket instead of four DIP-20 sockets for that kind of upgrade, and required just a single "256K x 16 FPM dual CAS" chip, which exist at speeds down to 25ns, and should be easier to obtain at 40ns to 50ns than DIP20 chips. This is no use for you unless you design an adapter PCB for your board, though...