Performance
So, the Thunderbird brings a smaller, faster L2 cache with it. Does this help performance? Let's see. I used my favourite SlotA motherboard, Abit's KA7 (reviewed here) with a stick of Corsair PC133 CAS2 memory (reviewed here) running at FSB+PCI (so 133MHz). The video card was MSI's AGPhantom 8809, a GeForce SDR card.

Firstl, a completely synthetic benchmark in the form of SiSoft Sandra (get it here):

Hmm, not much difference there. A slightly higher memory score from the Thunderbird is the most interesting bit, but it's strange how the "A" Athlon lags behind the older "C" model. Now for some real-world benchmarking, firstly Quake3 Demo1:

In High Quality my GeForce SDR is maxing out in a big way, so the CPU becomes irrelevant. However, again we see the "A" Athlon lagging slightly and the Thunderbird slightly ahead - again, only very slightly, though.. finally, MadOnion's 3DMark2000:

Same deal. Again, the A Athlon lags ever-so-slightly behind, while the Thunderbird shows marginally higher performance across the board. The difference is fairly trivial still, though.

As a futher test, I set the L2 cache on the "A" Athlon back to 1/3 ratio, and cranked both it and the Thunderbird up to 115MHz FSB, or 805MHz core speed. This "artificial" test will show if the slower cache makes much difference to the high-end chips such as the 1GHz units, where this difference in L2 cache speeds really exists.