I'm following, but not super closely.. Doing Result capture like this, are you using good capacitors (2, 5, at most 10%) or are you using standard +80%/-20% caps? If you're having to tinker with values that much, then variance between the parts that people buy is going to be a real issue..
Add-On: I just looked.. the 30pF is a 5% part, so that's a plus.. I would still suggest buying a few of the same part number from different vendors (to guarantee you get samples from different manufacturing lots) and make sure the variance doesn't cause issues..
Enigma
The different parts I've tried have been very different values. 30pF was my original design. But then when I had many capture errors I decided to try larger values like 100pF, 220pF and 330pF. At 128 MHz 220pF worked well. But then when I tried boosting to 256 or 300 MHz I couldn't get capture because the delays were too long and one bit ran into another. So I started lowering again and ended up back at 30pF. So if I had just started running at 256MHz with the original cap I would have avoided all this. I think it's silly to make the serial comm data rate dependent on the internal hash clock, especially when there's the input 32 MHz clock available. Maybe they had to pay by the flip flop for design and decided to save 32 of them.
I hope the BitFury chip has a more flexible design. Addressable registers using SPI like flash memory would be ideal. Then you just update the data you need for each work unit. Nonce ranges and operating parameters like clock cfg can be set once and left. Most current micro-controllers have hardware support for that.
Bitfury.... drooooooool......
Hope you rest in between sets and work BKKCoins. Keep fresh!