\subsection{Architecture: amd64}
\label{sec:isa_amd64}

All three seeds' cells for amd64 combined: 1{,}440 rows, zero errors. Seed remains the dominant source of variation within this architecture alone (Kruskal-Wallis $H=50.76$, $p=9.51e-12$) -- identical in shape to the other two architectures (see \S\ref{sec:isa_amd64}--\ref{sec:isa_riscv64}).

\begin{figure}[h]
\centering
\includegraphics[width=0.75\textwidth]{isa_amd64_seed_violin_light.pdf}
\caption{amd64: infer\_dec\_q distribution by seed (violin + inner boxplot).}
\end{figure}

\begin{table}[h]
\centering
\caption{Per-seed summary, amd64.}
\begin{tabular}{lrrrr}
\toprule
seed & mean & sd & median & early-exit rate \\
\midrule
12345 & 56.85 & 29.30 & 68.0 & 0.988 \\
67890 & 28.09 & 38.34 & 0.0 & 0.990 \\
13579 & 44.50 & 35.48 & 68.0 & 0.992 \\
\bottomrule
\end{tabular}
\end{table}

\begin{table}[h]
\centering
\caption{Per-factor main-effect means, amd64 (all seeds pooled).}
\begin{tabular}{lrrrr}
\toprule
factor & mean (hi) & mean (lo) & difference \\
\midrule
entropy & 43.80 & 42.50 & 1.30 \\
coeff.\ of variation & 43.11 & 43.18 & -0.07 \\
temporal decay & 43.39 & 42.90 & 0.49 \\
stability & 43.52 & 42.77 & 0.75 \\
\bottomrule
\end{tabular}
\end{table}

\clearpage