GPU & hardware
Throwing silicon at the wall: GPU ports, FPGA pipelines, distributed sweeps, and the perennial quantum proposal. This is the ledger of what each one actually delivered, and why the wall it meets is memory and structure, not arithmetic.
Eternity II looks like the perfect GPU workload: millions of independent subtrees, embarrassingly parallel. Eighteen years of community attempts measured a different reality: divergent branching, per-thread state that outgrows fast memory, and a placement loop that was already memory-bound on CPUs. What the GPUs actually delivered, and the one workload where they genuinely shine.
If the placement loop is memory-latency-bound, an FPGA looks like the exact answer: put the lookup tables in on-chip block RAM one cycle away, and pipeline dozens of tiny backtrackers on one die. The community mapped this road in detail. Michael Field designed the solver, projected 5 billion placements per second per chip, and ran a prototype on real silicon. Then the road was never driven to the end. The complete record, and why.
The quantum computer is the list's oldest deus ex machina, invoked in the puzzle's first month and every few years since. There are exactly two real stories to tell: Grover's quadratic speedup, and annealing on a QUBO encoding. This page tells both properly, does the arithmetic against Eternity II's actual numbers, and reports the complete community record: nineteen years of asides, one unfinished embedding attempt, zero runs.