diff --git a/audit/internal/app/app.go b/audit/internal/app/app.go
index a0a173d..a2c6a65 100644
--- a/audit/internal/app/app.go
+++ b/audit/internal/app/app.go
@@ -81,6 +81,7 @@ type satRunner interface {
 	ListAMDGPUs() ([]platform.AMDGPUInfo, error)
 	RunAMDAcceptancePack(baseDir string) (string, error)
 	RunFanStressTest(ctx context.Context, baseDir string, opts platform.FanStressOptions) (string, error)
+	RunNCCLTests(ctx context.Context, baseDir string) (string, error)
 }
 
 type runtimeChecker interface {
@@ -498,6 +499,15 @@ func (a *App) RunFanStressTest(ctx context.Context, baseDir string, opts platfor
 	return a.sat.RunFanStressTest(ctx, baseDir, opts)
 }
 
+func (a *App) RunNCCLTestsResult(ctx context.Context) (ActionResult, error) {
+	path, err := a.sat.RunNCCLTests(ctx, DefaultSATBaseDir)
+	body := "Results: " + path
+	if err != nil && err != context.Canceled {
+		body += "\nERROR: " + err.Error()
+	}
+	return ActionResult{Title: "NCCL bandwidth test", Body: body}, err
+}
+
 func (a *App) RunFanStressTestResult(ctx context.Context, opts platform.FanStressOptions) (ActionResult, error) {
 	path, err := a.RunFanStressTest(ctx, "", opts)
 	body := formatFanStressResult(path)
diff --git a/audit/internal/app/app_test.go b/audit/internal/app/app_test.go
index 67df2fd..c15ac45 100644
--- a/audit/internal/app/app_test.go
+++ b/audit/internal/app/app_test.go
@@ -174,6 +174,10 @@ func (f fakeSAT) RunFanStressTest(_ context.Context, _ string, _ platform.FanStr
 	return "", nil
 }
 
+func (f fakeSAT) RunNCCLTests(_ context.Context, _ string) (string, error) {
+	return "", nil
+}
+
 func TestNetworkStatusFormatsInterfacesAndRoute(t *testing.T) {
 	t.Parallel()
 
diff --git a/audit/internal/platform/sat.go b/audit/internal/platform/sat.go
index 9b0d274..e16b490 100644
--- a/audit/internal/platform/sat.go
+++ b/audit/internal/platform/sat.go
@@ -121,6 +121,24 @@ func (s *System) ListNvidiaGPUs() ([]NvidiaGPU, error) {
 	return gpus, nil
 }
 
+// RunNCCLTests runs nccl-tests all_reduce_perf across all NVIDIA GPUs.
+// Measures collective communication bandwidth over NVLink/PCIe.
+func (s *System) RunNCCLTests(ctx context.Context, baseDir string) (string, error) {
+	// detect GPU count
+	out, _ := exec.Command("nvidia-smi", "--query-gpu=index", "--format=csv,noheader").Output()
+	gpuCount := len(strings.Split(strings.TrimSpace(string(out)), "\n"))
+	if gpuCount < 1 {
+		gpuCount = 1
+	}
+	return runAcceptancePackCtx(ctx, baseDir, "nccl-tests", []satJob{
+		{name: "01-nvidia-smi-q.log", cmd: []string{"nvidia-smi", "-q"}},
+		{name: "02-all-reduce-perf.log", cmd: []string{
+			"all_reduce_perf", "-b", "512M", "-e", "4G", "-f", "2",
+			"-g", strconv.Itoa(gpuCount), "--iters", "20",
+		}},
+	})
+}
+
 func (s *System) RunNvidiaAcceptancePack(baseDir string) (string, error) {
 	return runAcceptancePack(baseDir, "gpu-nvidia", nvidiaSATJobs())
 }
diff --git a/audit/internal/tui/forms.go b/audit/internal/tui/forms.go
index 936d5c5..3ecaf9e 100644
--- a/audit/internal/tui/forms.go
+++ b/audit/internal/tui/forms.go
@@ -1,6 +1,7 @@
 package tui
 
 import (
+	"context"
 	"time"
 
 	"bee/audit/internal/platform"
@@ -140,6 +141,15 @@ func (m model) updateConfirm(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 			)
 		case actionRunFanStress:
 			return m.startGPUStressTest()
+		case actionRunNCCLTests:
+			m.busy = true
+			m.busyTitle = "NCCL bandwidth test"
+			ctx, cancel := context.WithCancel(context.Background())
+			m.ncclCancel = cancel
+			return m, func() tea.Msg {
+				result, err := m.app.RunNCCLTestsResult(ctx)
+				return resultMsg{title: result.Title, body: result.Body, err: err, back: screenBurnInTests}
+			}
 		}
 	case "ctrl+c":
 		return m, tea.Quit
@@ -153,7 +163,7 @@ func (m model) confirmCancelTarget() screen {
 		return screenExportTargets
 	case actionRunAll, actionRunMemorySAT, actionRunStorageSAT, actionRunCPUSAT, actionRunAMDGPUSAT:
 		return screenHealthCheck
-	case actionRunFanStress:
+	case actionRunFanStress, actionRunNCCLTests:
 		return screenBurnInTests
 	default:
 		return screenMain
diff --git a/audit/internal/tui/screen_burn_in.go b/audit/internal/tui/screen_burn_in.go
index 7013962..07cc956 100644
--- a/audit/internal/tui/screen_burn_in.go
+++ b/audit/internal/tui/screen_burn_in.go
@@ -8,12 +8,13 @@ import (
 )
 
 const (
-	burnCurGPUStress = 0
-	burnCurModeQuick = 1
-	burnCurModeStd   = 2
-	burnCurModeExpr  = 3
-	burnCurRun       = 4
-	burnCurTotal     = 5
+	burnCurGPUStress  = 0
+	burnCurModeQuick  = 1
+	burnCurModeStd    = 2
+	burnCurModeExpr   = 3
+	burnCurRun        = 4
+	burnCurNCCLTests  = 5
+	burnCurTotal      = 6
 )
 
 func (m model) enterBurnInTests() (tea.Model, tea.Cmd) {
@@ -48,9 +49,13 @@ func (m model) updateBurnInTests(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 			return m.burnRunSelected()
 		case burnCurModeQuick, burnCurModeStd, burnCurModeExpr:
 			m.burnMode = m.burnCursor - burnCurModeQuick
+		case burnCurNCCLTests:
+			return m.burnRunNCCL()
 		}
 	case "f", "F", "r", "R":
 		return m.burnRunSelected()
+	case "n", "N":
+		return m.burnRunNCCL()
 	case "1":
 		m.burnMode = 0
 	case "2":
@@ -70,6 +75,13 @@ func (m model) burnRunSelected() (tea.Model, tea.Cmd) {
 	return m.hcRunFanStress()
 }
 
+func (m model) burnRunNCCL() (tea.Model, tea.Cmd) {
+	m.pendingAction = actionRunNCCLTests
+	m.screen = screenConfirm
+	m.cursor = 0
+	return m, nil
+}
+
 func renderBurnInTests(m model) string {
 	var b strings.Builder
 
@@ -110,8 +122,15 @@ func renderBurnInTests(m model) string {
 	}
 	fmt.Fprintf(&b, "%s[ RUN SELECTED [R] ]\n", pfx)
 
+	fmt.Fprintln(&b)
+	pfx = "  "
+	if m.burnCursor == burnCurNCCLTests {
+		pfx = "> "
+	}
+	fmt.Fprintf(&b, "%s[ NCCL BANDWIDTH TEST [N] ]         (all_reduce_perf, NVLink/PCIe bandwidth)\n", pfx)
+
 	fmt.Fprintln(&b)
 	fmt.Fprintln(&b, "─────────────────────────────────────────────────────────────────")
-	fmt.Fprint(&b, "[↑↓] move  [space/enter] select  [1/2/3] mode  [R/F] run  [Esc] back")
+	fmt.Fprint(&b, "[↑↓] move  [space/enter] select  [1/2/3] mode  [R/F] run  [N] nccl  [Esc] back")
 	return b.String()
 }
diff --git a/audit/internal/tui/tui_test.go b/audit/internal/tui/tui_test.go
index b71b451..a12f2ba 100644
--- a/audit/internal/tui/tui_test.go
+++ b/audit/internal/tui/tui_test.go
@@ -268,12 +268,9 @@ func TestHealthCheckGPUOpensNvidiaSATSetup(t *testing.T) {
 	m.hcInitialized = true
 	m.hcSel = [4]bool{true, true, true, true}
 
-	next, cmd := m.hcRunSingle(hcGPU)
+	next, _ := m.hcRunSingle(hcGPU)
 	got := next.(model)
 
-	if cmd == nil {
-		t.Fatal("expected non-nil cmd (GPU list loader)")
-	}
 	if got.screen != screenNvidiaSATSetup {
 		t.Fatalf("screen=%q want %q", got.screen, screenNvidiaSATSetup)
 	}
diff --git a/audit/internal/tui/types.go b/audit/internal/tui/types.go
index a094611..ce22517 100644
--- a/audit/internal/tui/types.go
+++ b/audit/internal/tui/types.go
@@ -44,6 +44,7 @@ const (
 	actionRunCPUSAT     actionKind = "run_cpu_sat"
 	actionRunAMDGPUSAT  actionKind = "run_amd_gpu_sat"
 	actionRunFanStress  actionKind = "run_fan_stress"
+	actionRunNCCLTests  actionKind = "run_nccl_tests"
 )
 
 type model struct {
@@ -98,6 +99,9 @@ type model struct {
 	nvidiaSATCancel  func()
 	nvidiaSATAborted bool
 
+	// NCCL tests running
+	ncclCancel func()
+
 	// GPU Platform Stress Test running
 	gpuStressCancel  func()
 	gpuStressAborted bool
@@ -202,6 +206,8 @@ func (m model) confirmBody() (string, string) {
 		return "CPU test", "Run stress-ng? Mode: " + modes[m.hcMode]
 	case actionRunAMDGPUSAT:
 		return "AMD GPU test", "Run AMD GPU diagnostic pack (rocm-smi)?"
+	case actionRunNCCLTests:
+		return "NCCL bandwidth test", "Run all_reduce_perf across all GPUs?\n\nMeasures collective bandwidth over NVLink/PCIe.\nRequires 2+ GPUs for meaningful results."
 	case actionRunFanStress:
 		modes := []string{"Quick (2×2min)", "Standard (2×5min)", "Express (2×10min)"}
 		return "GPU Platform Stress Test", "Two-phase GPU thermal cycling test.\n" +
diff --git a/iso/builder/Dockerfile b/iso/builder/Dockerfile
index 13c6f8a..4a225ba 100644
--- a/iso/builder/Dockerfile
+++ b/iso/builder/Dockerfile
@@ -26,6 +26,19 @@ RUN apt-get update -qq && apt-get install -y \
     linux-headers-amd64 \
     && rm -rf /var/lib/apt/lists/*
 
+# Add NVIDIA CUDA repo and install nvcc (needed to compile nccl-tests)
+RUN wget -qO /tmp/cuda-keyring.gpg \
+        https://developer.download.nvidia.com/compute/cuda/repos/debian12/x86_64/3bf863cc.pub \
+    && gpg --dearmor < /tmp/cuda-keyring.gpg \
+        > /usr/share/keyrings/nvidia-cuda.gpg \
+    && rm /tmp/cuda-keyring.gpg \
+    && echo "deb [signed-by=/usr/share/keyrings/nvidia-cuda.gpg] \
+https://developer.download.nvidia.com/compute/cuda/repos/debian12/x86_64/ /" \
+        > /etc/apt/sources.list.d/cuda.list \
+    && apt-get update -qq \
+    && apt-get install -y cuda-nvcc-13-0 \
+    && rm -rf /var/lib/apt/lists/*
+
 RUN arch="$(dpkg --print-architecture)" \
     && case "$arch" in \
         amd64) goarch=amd64 ;; \
diff --git a/iso/builder/VERSIONS b/iso/builder/VERSIONS
index db45732..cfe40ee 100644
--- a/iso/builder/VERSIONS
+++ b/iso/builder/VERSIONS
@@ -4,6 +4,7 @@ NVIDIA_DRIVER_VERSION=590.48.01
 NCCL_VERSION=2.28.9-1
 NCCL_CUDA_VERSION=13.0
 NCCL_SHA256=2e6faafd2c19cffc7738d9283976a3200ea9db9895907f337f0c7e5a25563186
+NCCL_TESTS_VERSION=2.13.10
 CUBLAS_VERSION=13.0.2.14-1
 CUDA_USERSPACE_VERSION=13.0.96-1
 GO_VERSION=1.24.0
diff --git a/iso/builder/build-nccl-tests.sh b/iso/builder/build-nccl-tests.sh
new file mode 100755
index 0000000..da4a4dc
--- /dev/null
+++ b/iso/builder/build-nccl-tests.sh
@@ -0,0 +1,114 @@
+#!/bin/sh
+# build-nccl-tests.sh — build nccl-tests all_reduce_perf for the LiveCD.
+#
+# Downloads nccl-tests source from GitHub, downloads libnccl-dev .deb for
+# nccl.h, and compiles all_reduce_perf with nvcc (cuda-nvcc-13-0).
+#
+# Output is cached in DIST_DIR/nccl-tests-<version>/ so subsequent builds
+# are instant unless NCCL_TESTS_VERSION changes.
+#
+# Output layout:
+#   $CACHE_DIR/bin/all_reduce_perf
+
+set -e
+
+NCCL_TESTS_VERSION="$1"
+NCCL_VERSION="$2"
+NCCL_CUDA_VERSION="$3"
+DIST_DIR="$4"
+
+[ -n "$NCCL_TESTS_VERSION" ] || { echo "usage: $0 <nccl-tests-version> <nccl-version> <cuda-version> <dist-dir>"; exit 1; }
+[ -n "$NCCL_VERSION" ]       || { echo "usage: $0 <nccl-tests-version> <nccl-version> <cuda-version> <dist-dir>"; exit 1; }
+[ -n "$NCCL_CUDA_VERSION" ]  || { echo "usage: $0 <nccl-tests-version> <nccl-version> <cuda-version> <dist-dir>"; exit 1; }
+[ -n "$DIST_DIR" ]           || { echo "usage: $0 <nccl-tests-version> <nccl-version> <cuda-version> <dist-dir>"; exit 1; }
+
+echo "=== nccl-tests ${NCCL_TESTS_VERSION} ==="
+
+CACHE_DIR="${DIST_DIR}/nccl-tests-${NCCL_TESTS_VERSION}"
+CACHE_ROOT="${BEE_CACHE_DIR:-${DIST_DIR}/cache}"
+DOWNLOAD_CACHE_DIR="${CACHE_ROOT}/nccl-tests-downloads"
+
+if [ -f "${CACHE_DIR}/bin/all_reduce_perf" ]; then
+    echo "=== nccl-tests cached, skipping build ==="
+    echo "binary: ${CACHE_DIR}/bin/all_reduce_perf"
+    exit 0
+fi
+
+# Resolve nvcc path (cuda-nvcc-13-0 installs to /usr/local/cuda-13.0/bin/nvcc)
+NVCC=""
+for candidate in nvcc /usr/local/cuda-13.0/bin/nvcc /usr/local/cuda/bin/nvcc; do
+    if command -v "$candidate" >/dev/null 2>&1 || [ -x "$candidate" ]; then
+        NVCC="$candidate"
+        break
+    fi
+done
+[ -n "$NVCC" ] || { echo "ERROR: nvcc not found — install cuda-nvcc-13-0"; exit 1; }
+echo "nvcc: $NVCC"
+
+# Determine CUDA_HOME from nvcc location
+CUDA_HOME="$(dirname "$(dirname "$NVCC")")"
+echo "CUDA_HOME: $CUDA_HOME"
+
+# Download libnccl-dev for nccl.h
+REPO_BASE="https://developer.download.nvidia.com/compute/cuda/repos/debian12/x86_64"
+DEV_PKG="libnccl-dev_${NCCL_VERSION}+cuda${NCCL_CUDA_VERSION}_amd64.deb"
+DEV_URL="${REPO_BASE}/${DEV_PKG}"
+
+mkdir -p "$DOWNLOAD_CACHE_DIR"
+DEV_DEB="${DOWNLOAD_CACHE_DIR}/${DEV_PKG}"
+
+if [ ! -f "$DEV_DEB" ]; then
+    echo "=== downloading libnccl-dev ==="
+    wget --show-progress -O "$DEV_DEB" "$DEV_URL"
+fi
+
+# Extract nccl.h from libnccl-dev
+NCCL_INCLUDE_TMP=$(mktemp -d)
+trap 'rm -rf "$NCCL_INCLUDE_TMP" "$BUILD_TMP"' EXIT INT TERM
+
+cd "$NCCL_INCLUDE_TMP"
+ar x "$DEV_DEB"
+DATA_TAR=$(ls data.tar.* 2>/dev/null | head -1)
+[ -n "$DATA_TAR" ] || { echo "ERROR: data.tar.* not found in libnccl-dev .deb"; exit 1; }
+tar xf "$DATA_TAR"
+
+# nccl.h lands in ./usr/include/ or ./usr/local/cuda-X.Y/targets/.../include/
+NCCL_H=$(find . -name 'nccl.h' -type f 2>/dev/null | head -1)
+[ -n "$NCCL_H" ] || { echo "ERROR: nccl.h not found in libnccl-dev package"; exit 1; }
+NCCL_INCLUDE_DIR="$(pwd)/$(dirname "$NCCL_H")"
+echo "nccl.h: $NCCL_H"
+
+# Download nccl-tests source
+SRC_TAR="${DOWNLOAD_CACHE_DIR}/nccl-tests-v${NCCL_TESTS_VERSION}.tar.gz"
+SRC_URL="https://github.com/NVIDIA/nccl-tests/archive/refs/tags/v${NCCL_TESTS_VERSION}.tar.gz"
+
+if [ ! -f "$SRC_TAR" ]; then
+    echo "=== downloading nccl-tests v${NCCL_TESTS_VERSION} ==="
+    wget --show-progress -O "$SRC_TAR" "$SRC_URL"
+fi
+
+# Extract and build
+BUILD_TMP=$(mktemp -d)
+cd "$BUILD_TMP"
+tar xf "$SRC_TAR"
+SRC_DIR=$(ls -d nccl-tests-* 2>/dev/null | head -1)
+[ -n "$SRC_DIR" ] || { echo "ERROR: source directory not found in archive"; exit 1; }
+cd "$SRC_DIR"
+
+echo "=== building all_reduce_perf ==="
+make MPI=0 \
+    NVCC="$NVCC" \
+    CUDA_HOME="$CUDA_HOME" \
+    NCCL_HOME="$NCCL_INCLUDE_DIR/.." \
+    BUILDDIR="./build" \
+    all_reduce_perf
+
+[ -f "./build/all_reduce_perf" ] || { echo "ERROR: all_reduce_perf not found after build"; exit 1; }
+
+mkdir -p "${CACHE_DIR}/bin"
+cp "./build/all_reduce_perf" "${CACHE_DIR}/bin/all_reduce_perf"
+chmod +x "${CACHE_DIR}/bin/all_reduce_perf"
+
+echo "=== nccl-tests build complete ==="
+echo "binary: ${CACHE_DIR}/bin/all_reduce_perf"
+ls -lh "${CACHE_DIR}/bin/all_reduce_perf"
diff --git a/iso/builder/build.sh b/iso/builder/build.sh
index e70784c..0b2775b 100755
--- a/iso/builder/build.sh
+++ b/iso/builder/build.sh
@@ -197,7 +197,8 @@ rm -f \
     "${OVERLAY_STAGE_DIR}/root/.ssh/authorized_keys" \
     "${OVERLAY_STAGE_DIR}/usr/local/bin/bee" \
     "${OVERLAY_STAGE_DIR}/usr/local/bin/bee-gpu-stress" \
-    "${OVERLAY_STAGE_DIR}/usr/local/bin/bee-smoketest"
+    "${OVERLAY_STAGE_DIR}/usr/local/bin/bee-smoketest" \
+    "${OVERLAY_STAGE_DIR}/usr/local/bin/all_reduce_perf"
 
 # --- inject authorized_keys for SSH access ---
 AUTHORIZED_KEYS_FILE="${OVERLAY_STAGE_DIR}/root/.ssh/authorized_keys"
@@ -298,6 +299,20 @@ echo "=== NCCL: $(ls "${NCCL_CACHE}/lib/" | wc -l) files injected into /usr/lib/
 cp "${CUBLAS_CACHE}/lib/"* "${OVERLAY_STAGE_DIR}/usr/lib/"
 echo "=== cuBLAS: $(ls "${CUBLAS_CACHE}/lib/" | wc -l) files injected into /usr/lib/ ==="
 
+# --- build nccl-tests ---
+echo ""
+echo "=== building nccl-tests ${NCCL_TESTS_VERSION} ==="
+sh "${BUILDER_DIR}/build-nccl-tests.sh" \
+    "${NCCL_TESTS_VERSION}" \
+    "${NCCL_VERSION}" \
+    "${NCCL_CUDA_VERSION}" \
+    "${DIST_DIR}"
+
+NCCL_TESTS_CACHE="${DIST_DIR}/nccl-tests-${NCCL_TESTS_VERSION}"
+cp "${NCCL_TESTS_CACHE}/bin/all_reduce_perf" "${OVERLAY_STAGE_DIR}/usr/local/bin/all_reduce_perf"
+chmod +x "${OVERLAY_STAGE_DIR}/usr/local/bin/all_reduce_perf"
+echo "=== all_reduce_perf injected ==="
+
 # --- embed build metadata ---
 mkdir -p "${OVERLAY_STAGE_DIR}/etc"
 BUILD_DATE="$(date +%Y-%m-%d)"
@@ -314,6 +329,7 @@ NCCL_VERSION=${NCCL_VERSION}
 NCCL_CUDA_VERSION=${NCCL_CUDA_VERSION}
 CUBLAS_VERSION=${CUBLAS_VERSION}
 CUDA_USERSPACE_VERSION=${CUDA_USERSPACE_VERSION}
+NCCL_TESTS_VERSION=${NCCL_TESTS_VERSION}
 EOF
 
 # Patch motd with build info