diff --git a/app/ui/features/settings/modules.js b/app/ui/features/settings/modules.js
index 6354cfa7..05c59f08 100644
--- a/app/ui/features/settings/modules.js
+++ b/app/ui/features/settings/modules.js
@@ -18,7 +18,7 @@ export const modules = (app) => function mount() {
   };
   const addonRow = (a) => {
     const pending = a.state === "pending";
-    const hint = [a.hint, pending ? RESTART_HINT : null, a.failed ? `Could not install: ${a.failed}\nSwitch it off and on to try again.` : null].filter(Boolean).join("\n");
+    const hint = [a.hint, pending ? RESTART_HINT : null, a.failed ? `Could not install: ${a.failed}\nSwitch it on to try again.` : null].filter(Boolean).join("\n");
     return c.toggle.default({ label: a.title, hint, checked: a.state === "installed" || pending, onChange: (on) => flip(a, on) });
   };
 
diff --git a/app/ui/features/upscale/index.js b/app/ui/features/upscale/index.js
index c73a2845..d8b90483 100644
--- a/app/ui/features/upscale/index.js
+++ b/app/ui/features/upscale/index.js
@@ -35,7 +35,9 @@ export default {
     }
 
     async function run(media, pressed = false) {
-      const model = rtxOn() ? RTX : p.pref("upscaleModel", "");
+      // RTX only counts when this machine has it on right now: a project saved elsewhere may still say "rtx"
+      const rtxHere = rtxOn() && await app.api.upscaleModels().then((r) => Boolean(r.rtx)).catch(() => false);
+      const model = rtxOn() ? (rtxHere ? RTX : "") : p.pref("upscaleModel", "");
       if (!media || media.subfolder === UPSCALED) return;                    // never upscale twice
       if (!model) return pressed ? suggest() : c.toast.warn({ text: "Upscale: pick a model or NVIDIA RTX Super Resolution in Settings ▸ Editor." });
       const key = keyOf(media), pid = p.project.id;
@@ -86,8 +88,8 @@ export default {
               options: [{ value: "scale", label: "Scale by multiplier" }, { value: "size", label: "Target dimensions" }] }) }),
             ...(o.resize === "scale"
               ? [c.settingsRow.default({ label: "Scale", hint: "1 to 4 times.", control: c.slider.readout({ label: "Scale", value: o.scale, min: 1, max: 4, step: 0.05, precision: 2, onCommit: (v) => set("scale", v) }) })]
-              : [c.settingsRow.default({ label: "Width", hint: "In pixels, 64 to 8192.", control: c.number.md({ label: "Width", value: o.width, min: 64, max: 8192, step: 8, precision: 0, onChange: (v) => set("width", v) }) }),
-                 c.settingsRow.default({ label: "Height", hint: "In pixels, 64 to 8192.", control: c.number.md({ label: "Height", value: o.height, min: 64, max: 8192, step: 8, precision: 0, onChange: (v) => set("height", v) }) })])]),
+              : [c.settingsRow.default({ label: "Width", hint: "In pixels, 64 to 8192. Rounded to a multiple of 8.", control: c.number.md({ label: "Width", value: o.width, min: 64, max: 8192, step: 8, precision: 0, onChange: (v) => set("width", v) }) }),
+                 c.settingsRow.default({ label: "Height", hint: "In pixels, 64 to 8192. Rounded to a multiple of 8.", control: c.number.md({ label: "Height", value: o.height, min: 64, max: 8192, step: 8, precision: 0, onChange: (v) => set("height", v) }) })])]),
           c.settingsRow.default({ label: "Strength", hint: "How much of the effect to apply.", control: c.slider.readout({ label: "Strength", value: o.strength, min: 0, max: 1, step: 0.05, precision: 2, onCommit: (v) => set("strength", v) }) }),
           c.toggle.default({ label: "10-bit processing", hint: "More precise colour inside the upscale. The saved video stays 8-bit.", checked: o.tenbit, onChange: (v) => set("tenbit", v) }),
         ];
diff --git a/core/addons.py b/core/addons.py
index ccbd9462..7448cbb2 100644
--- a/core/addons.py
+++ b/core/addons.py
@@ -33,7 +33,7 @@ def _nvidia_gpu() -> bool:
         return False
     try:
         import torch
-        return bool(torch.cuda.is_available() and torch.version.cuda)
+        return bool(torch.cuda.is_available() and torch.version.cuda and torch.cuda.get_device_capability() >= (7, 5))   # RTX starts at Turing
     except Exception:  # noqa: BLE001
         return False
 
@@ -94,7 +94,7 @@ def listing() -> list[dict]:
             continue
         here, want = _present(a), a["id"] in wanted
         out.append({"id": a["id"], "title": a["title"], "hint": a["hint"],
-                    "state": ("installed" if here else "pending") if want else ("disabled" if here else "available"),
+                    "state": ("installed" if here else "available" if failed.get(a["id"]) else "pending") if want else ("disabled" if here else "available"),   # a failed install is offered again, not "pending"
                     "failed": failed.get(a["id"]) if not here else None})
     return out
 
diff --git a/core/tests/test_addons.py b/core/tests/test_addons.py
index 8882e037..2dd086c6 100644
--- a/core/tests/test_addons.py
+++ b/core/tests/test_addons.py
@@ -71,7 +71,8 @@ def test_a_failed_install_is_said_and_not_retried_until_switched_off_and_on(here
     monkeypatch.setattr(update, "install_lines", lambda lines: ran.append(1) or {"ok": False, "detail": "no wheel for this Python"})
     addons.set_wanted("nvidia_vsr", True)
     addons.install_wanted()
-    assert next(a for a in addons.listing() if a["id"] == "nvidia_vsr")["failed"] == "no wheel for this Python"
+    row = next(a for a in addons.listing() if a["id"] == "nvidia_vsr")
+    assert row["failed"] == "no wheel for this Python" and row["state"] == "available", "a failed install must not read as waiting for a restart"
     addons.install_wanted()
     assert len(ran) == 1, "a broken install would be retried on every start"
     addons.set_wanted("nvidia_vsr", False)
diff --git a/modules/output/render/rtx.py b/modules/output/render/rtx.py
index cba39c38..4a88d0e4 100644
--- a/modules/output/render/rtx.py
+++ b/modules/output/render/rtx.py
@@ -32,7 +32,8 @@ def options(raw) -> dict:
     for key, lo, hi in (("scale", 1.0, 4.0), ("strength", 0.0, 1.0), ("width", 64, 8192), ("height", 64, 8192)):
         if not isinstance(o[key], (int, float)) or isinstance(o[key], bool) or not lo <= o[key] <= hi:
             raise ValueError(f"RTX {key} must be a number from {lo} to {hi}.")
-    o["tenbit"] = bool(o["tenbit"])
+    if not isinstance(o["tenbit"], bool):
+        raise ValueError("RTX tenbit must be true or false.")
     return o
 
 
diff --git a/modules/output/render/tests/test_upscale.py b/modules/output/render/tests/test_upscale.py
index 0956cbaa..a00a1b7b 100644
--- a/modules/output/render/tests/test_upscale.py
+++ b/modules/output/render/tests/test_upscale.py
@@ -51,7 +51,7 @@ from modules.output.render import rtx  # noqa: E402
 def test_rtx_options_are_checked_by_name():
     assert rtx.options("{}")["quality"] == "ULTRA"
     assert rtx.options({"scale": 3, "quality": "DEBLUR_HIGH"})["scale"] == 3
-    for bad in ({"quality": "ULTRAA"}, {"scale": 5}, {"strength": -1}, {"resize": "huge"}, {"width": 8}):
+    for bad in ({"quality": "ULTRAA"}, {"scale": 5}, {"strength": -1}, {"resize": "huge"}, {"width": 8}, {"tenbit": "false"}):
         with pytest.raises(ValueError):
             rtx.options(bad)
     with pytest.raises(ValueError):