I had a blast back in the day with 955BE and Giga 890FX UD7 plus some Hypers My scores from XS low clock challenge are not visible anymore because the photos don't exist, but I vividly remember the NB topping at 3100MHz @ 1.45VTT on air. Also my best scores were done at 890-900MHz RAM @ 6-6-5-17
We discussed a lot with chew* back then and he was telling me that for Thuban the best RAM are PSC, because you can push 1100MHz 7-9-7 for example.
Bus speed was lower, maybe about 225MHz. I remember some scores at 260MHz but I had a very hard time getting the CPU up there.