diff --git a/ci/test-matrix.yml b/ci/test-matrix.yml
index 35f02847ed7..a29f78e8a4e 100644
--- a/ci/test-matrix.yml
+++ b/ci/test-matrix.yml
@@ -17,51 +17,12 @@
 
 linux:
   pull-request:
+    # TEMPORARY: cut down to just Python 3.12 + CUDA 12.9.1 to debug the
+    # IPC re-export hang on r595 driver runners. Revert before merging.
     # linux-64
-    - { ARCH: 'amd64', PY_VER: '3.10',  CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 'v100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.10',  CUDA_VER: '13.0.2', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.10',  CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.11',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'rtxpro6000', GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.11',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.11',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
     - { ARCH: 'amd64', PY_VER: '3.12',  CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.12',  CUDA_VER: '13.0.2', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.12',  CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.13',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'v100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.13',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'rtxpro6000', GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.13',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'rtxpro6000', GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 't4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.14t', CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 't4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.14t', CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.14t', CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
     # linux-aarch64
-    - { ARCH: 'arm64', PY_VER: '3.10',  CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.10',  CUDA_VER: '13.0.2', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.10',  CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.11',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.11',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.11',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
     - { ARCH: 'arm64', PY_VER: '3.12',  CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.12',  CUDA_VER: '13.0.2', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.12',  CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.13',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.13',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.13',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.14',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.14',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.14',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.14t', CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.14t', CUDA_VER: '13.0.2', LOCAL_CTK: '0', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'arm64', PY_VER: '3.14t', CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest' }
-    # special runners
-    - { ARCH: 'amd64', PY_VER: '3.13',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'h100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.13',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'h100',       GPU_COUNT: '1', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 't4',         GPU_COUNT: '2', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.14t', CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'h100',       GPU_COUNT: '2', DRIVER: 'latest' }
-    - { ARCH: 'amd64', PY_VER: '3.11',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 't4',         GPU_COUNT: '1', DRIVER: 'latest', FLAVOR: 'wsl' }
-    - { ARCH: 'amd64', PY_VER: '3.12',  CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'rtx4090',    GPU_COUNT: '1', DRIVER: 'latest', FLAVOR: 'wsl' }
   nightly:
     # nightly-pytorch
     - { MODE: 'nightly-pytorch',    ARCH: 'amd64', PY_VER: '3.12', CUDA_VER: '12.6.3', LOCAL_CTK: '0', GPU: 'l4', GPU_COUNT: '1', DRIVER: 'latest', TORCH_VER: '2.11.0', TORCH_CUDA: 'cu126' }
@@ -83,28 +44,11 @@ linux:
 
 windows:
   pull-request:
+    # TEMPORARY: cut down to just Python 3.12 + CUDA 12.9.1 to keep the
+    # matrix non-empty while we debug the Linux IPC re-export hang.
+    # Revert before merging.
     # win-64
-    - { ARCH: 'amd64', PY_VER: '3.10',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'rtx2080',    GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'WDDM' }
-    - { ARCH: 'amd64', PY_VER: '3.10',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'rtxpro6000', GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'TCC' }
-    - { ARCH: 'amd64', PY_VER: '3.10',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'rtxpro6000', GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'TCC' }
-    - { ARCH: 'amd64', PY_VER: '3.11',  CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 'v100',       GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
-    - { ARCH: 'amd64', PY_VER: '3.11',  CUDA_VER: '13.0.2', LOCAL_CTK: '0', GPU: 'rtx4090',    GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'WDDM' }
-    - { ARCH: 'amd64', PY_VER: '3.11',  CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'rtx4090',    GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'WDDM' }
     - { ARCH: 'amd64', PY_VER: '3.12',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
-    - { ARCH: 'amd64', PY_VER: '3.12',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'TCC' }
-    - { ARCH: 'amd64', PY_VER: '3.12',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'TCC' }
-    - { ARCH: 'amd64', PY_VER: '3.13',  CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'TCC' }
-    - { ARCH: 'amd64', PY_VER: '3.13',  CUDA_VER: '13.0.2', LOCAL_CTK: '0', GPU: 'rtxpro6000', GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
-    - { ARCH: 'amd64', PY_VER: '3.13',  CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'rtxpro6000', GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '12.9.1', LOCAL_CTK: '0', GPU: 'v100',       GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'TCC' }
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '13.0.2', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
-    - { ARCH: 'amd64', PY_VER: '3.14t', CUDA_VER: '12.9.1', LOCAL_CTK: '1', GPU: 'l4',         GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'TCC' }
-    - { ARCH: 'amd64', PY_VER: '3.14t', CUDA_VER: '13.0.2', LOCAL_CTK: '0', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
-    - { ARCH: 'amd64', PY_VER: '3.14t', CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'a100',       GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
-    # special runners
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '13.2.1', LOCAL_CTK: '1', GPU: 't4',         GPU_COUNT: '2', DRIVER: 'latest', DRIVER_MODE: 'TCC' }
-    - { ARCH: 'amd64', PY_VER: '3.14',  CUDA_VER: '13.2.1', LOCAL_CTK: '0', GPU: 'h100',       GPU_COUNT: '2', DRIVER: 'latest', DRIVER_MODE: 'MCDM' }
   nightly:
     # nightly-pytorch
     - { MODE: 'nightly-pytorch',    ARCH: 'amd64', PY_VER: '3.12', CUDA_VER: '12.6.3', LOCAL_CTK: '0', GPU: 'l4', GPU_COUNT: '1', DRIVER: 'latest', DRIVER_MODE: 'TCC', TORCH_VER: '2.11.0',   TORCH_CUDA: 'cu126' }
diff --git a/ci/tools/env-vars b/ci/tools/env-vars
index 30fac1cdce8..19cc80ec700 100755
--- a/ci/tools/env-vars
+++ b/ci/tools/env-vars
@@ -88,7 +88,10 @@ elif [[ "${1}" == "test" ]]; then
   # We don't test compute-sanitizer on CTK<12 because backporting fixes is too much effort
   # We only test compute-sanitizer on python 3.12 arbitrarily; we don't need to use sanitizer on the entire matrix
   # Only local ctk installs have compute-sanitizer; there is no wheel for it
-  if [[ "${PY_VER}" == "3.12" && "${CUDA_VER}" != "11.8.0" && "${LOCAL_CTK}" == 1 && "${HOST_PLATFORM}" == linux* ]]; then
+  # TEMPORARY: force-disable compute-sanitizer to test whether it is the
+  # cause of the TestIpcReexport hang on r595-driver runners. Revert before
+  # merging.
+  if false && [[ "${PY_VER}" == "3.12" && "${CUDA_VER}" != "11.8.0" && "${LOCAL_CTK}" == 1 && "${HOST_PLATFORM}" == linux* ]]; then
     echo "LATEST_CUDA_VERSION=$(bash ci/tools/guess_latest.sh $TEST_CUDA_MAJOR)" >> $GITHUB_ENV
     SETUP_SANITIZER=1
   else