diff --git a/studio/frontend/src/features/chat/chat-settings-sheet.tsx b/studio/frontend/src/features/chat/chat-settings-sheet.tsx
index ecb6707a04..bd22cc4f55 100644
--- a/studio/frontend/src/features/chat/chat-settings-sheet.tsx
+++ b/studio/frontend/src/features/chat/chat-settings-sheet.tsx
@@ -723,11 +723,11 @@ export function ChatSettingsPanel({
   const autoLayers = isManual && gpuLayers < 0;
   // GPUs actually in use: the picked subset, or all visible when none picked.
   const gpusInUse = selectedGpuIds ?? gpuDevices.map((d) => d.index);
-  // TP is off with fewer than 2 GPUs in use (single GPU, or the picker narrowed
-  // to one): tensor split is a no-op there and aborts on some archs. Mirrors the
-  // multi-GPU gate on the GPU picker / Split ratio. (Under Auto layers the whole
-  // TP control is hidden -- llama.cpp's --fit aborts under --split-mode tensor.)
-  const tpDisabled = gpusInUse.length <= 1;
+  // The picker must keep one GPU selected.
+  const singleGpuInUse = gpusInUse.length <= 1;
+  // TP needs at least two GPUs because tensor split is a no-op on one and may
+  // abort. Auto layers hides TP because --fit aborts under --split-mode tensor.
+  const tpDisabled = singleGpuInUse;
   // Manual gpu-layers ceiling = model layer count + 1 (else a safe fallback):
   // llama.cpp counts the output layer as one more offloadable layer past the
   // repeating blocks ("offloaded 33/33" needs -ngl 33 on a 32-block model), so
@@ -1537,7 +1537,7 @@ export function ChatSettingsPanel({
                         Which GPUs this model may use. Unchecked GPUs are hidden
                         from llama.cpp (CUDA_VISIBLE_DEVICES, or
                         HIP_VISIBLE_DEVICES on ROCm). Leave all checked to use
-                        every GPU.
+                        every GPU. At least one GPU must stay selected.
                       </InfoHint>
                     </div>
                     <div className="flex flex-col gap-2">
@@ -1557,7 +1557,10 @@ export function ChatSettingsPanel({
                             checked={isGpuChecked(d.index)}
                             onCheckedChange={() => toggleGpu(d.index)}
                             data-test-id={`gpu-pick-${d.index}`}
-                            disabled={modelControlsDisabled}
+                            disabled={
+                              modelControlsDisabled ||
+                              (isGpuChecked(d.index) && singleGpuInUse)
+                            }
                           />
                         </div>
                       ))}