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Thanks! I am pleasantly surprised by just how effective a big ol' first-order RC filter can be. Time to get some of these out in the wild now.

PCI Vendor 1668 is Actiontec, whose bridge chip comes up in reference to the Sonnet Tempo Trio card. If that's what you have, very nice score. You could open the case and look. Edit: I think the reference to the Sonnet Tempo Trio I found in this thread may be a red herring. Actiontec makes...

I played around with Rs and Cs in LTSpice because it's a lot faster than trial and error with a soldering iron, and settled on 10 ohms and 4.7uF. That gives me the attenuation I want (down to <20mV) without dropping too much voltage: I had a 4.7uF part on hand; granted, in an 0805 package...

Funny, when researching the LTC6905 and jitter, I came across a few references to the Digilent BASYS2, which is a Xilinx Spartan 3 FPGA dev board: https://tilde.ini.uzh.ch/~tobi/wiki/doku.php?id=dig:fpga2#faq Apparently they had the same problem! Nice to know I'm not the only one.

It finally occurred to me to try measuring the peak-to-peak noise on the 5V input to the oscillator, and look at the FFT: I can't go >50MHz with the FFT on this scope so I might be missing some interesting things going on at higher frequencies, but as far as I can tell, I'm dealing with about...

I remembered I'd had problems with this style of PLCC socket being finicky before, so I tried reseating the 39VF020 a few times with no improvement. So I tried booting without the chip installed; still a bong and a black screen. I then tried removing the serial EEPROM, just to see what the card...

I was inspired to work on this a bit more yesterday. I tried a 4.7k 0805 resistor in place of the trim pot, and jitter did not improve. The trim pot is cermet, not wirewound, so it should have very low inductance and capacitance. Seems ideal for this application. I also observed that jitter is...

No, sorry, I shelved that board and have not returned to it. I tried 2 GLUE chips and got the same results on and off the board, so I do not suspect GLUE was the problem. I agree with your theory that it's likely a problem somewhere else on the board, perhaps one of the other chips, or a...

Unfortunately, these are the only two cards I have experience with, and I don't have any 1900x1200 DVI monitors at home to test with.

Points for you! Unfortunately...

@Powerbase dunno. I did enough searching to get here https://68kmla.org/bb/index.php?threads/soldering-new-vram-onto-quadra-630-motherboard.31632/post-523974 but don't have time to ingest that document at the moment.

My interpretation of those benchmarks is that the ATI graphics chip on the Gazelle board handily outperforms it's predecessor, Apple's Valkyrie chip on the Alchemy board, regardless of bus speed. I did not experience any stability issues with my Alchemy board at 50MHz.

There's an error in my table above that I wish I could correct; 16 (4 x 4) of the 56-ohm resistor packs are required, not 12. Not sure how I screwed up such basic math, must have been up late that night. Anyway, thinking I needed 12, I ordered 15 from Digi-Key, meaning I was one short. I angrily...

By the way, they did actually build and sell the red card, I found a sold Mercari listing as evidence: https://jp.mercari.com/item/m27008253405 LG52M3 is silkscreened on the upper right corner of the top of the board, if you search for that you'll find there was also a Kuroutoshikou version...

Initial results not good. I programmed the 39VF020, popped it in the socket, programmed the AT24C02D (not an 02B, surely it can't be that picky?), soldered to the board, installed in Quicksilver, I get a bong and a black screen. Never initializes video output. Out of patience for now, will come...

I checked the Winbond W9425G6EH and Elixir N2DS25616CT (which is Nanya, TIL) datasheets just to make sure there weren't any obvious incompatibilities. I found that Winbond specifies 2.5V +/- 0.2V for DDR400 (200MHz) but Nanya/Elixir wants 2.6V +/- 0.1V to run at that speed. It would probably be...

Woohoo, thanks! Hmm, who's chengansun? Regardless, I'll give it a try.

I wanted to play with some of the last/fastest classic Mac OS-compatible PCI video cards, so I managed to find a pair of Radeon 9250s. I feel like these used to be plentiful and cheap, but they seem to have gotten much rarer and more expensive. Of course, because I'm looking for projects, I only...