You just unboxed a shiny new PS5 or a beefy RTX-powered gaming rig. You plug it into your expensive Samsung QLED, fire up a game, and... wait. Why does the screen look washed out? Or worse, why is the console telling you that "your TV doesn't support HDR" when the box clearly said it does?
Honestly, it's one of the most annoying "hidden" hurdles in home entertainment. The culprit is usually a single setting buried three menus deep: Samsung Input Signal Plus.
If you've been searching for why your 4K 120Hz signal keeps dropping or why your Apple TV 4K isn't hitting its peak brightness, you've hit the right spot. This isn't just another tech gimmick. It is the literal "gatekeeper" for high-bandwidth data on Samsung displays.
What is Samsung Input Signal Plus anyway?
Basically, Samsung Input Signal Plus is a toggle that tells your TV to open the floodgates. By default, many Samsung HDMI ports are set to a "compatibility mode" that mimics older HDMI standards (like HDMI 1.4 or basic 2.0). This ensures that if you plug in a dusty old DVD player from 2005, it won't crash the system.
But modern devices—think Xbox Series X, high-end PCs, and 4K Blu-ray players—require way more bandwidth. We're talking about moving massive amounts of data for 10-bit color, HDR10+, and high frame rates. When you enable Samsung Input Signal Plus, you are expanding the input signal range for HDMI connections.
Without it, you're essentially trying to squeeze a fire hose worth of data through a straw.
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It used to be called "HDMI UHD Color" on models from 2018 and older. If you're rocking a classic MU or NU series, look for that name instead. On anything newer, like the Neo QLED S95C or the M8 Smart Monitor, it’s Input Signal Plus.
How to turn it on (And why it’s sometimes greyed out)
Finding the setting is a bit of a trek. Samsung likes to move things around, but for most 2022–2026 models, the path is pretty consistent.
- Grab your remote and hit the Home button.
- Navigate to Settings (sometimes called All Settings).
- Head over to Connection (or General on some versions).
- Find External Device Manager.
- There it is: Input Signal Plus.
Once you click it, you’ll see a list of your HDMI ports. You have to turn it on individually for each port where you’ve connected a high-performance device.
Wait, why is it greyed out?
I've seen this happen a lot. If you try to toggle the setting for a port that has nothing plugged into it, the TV might not let you click it. Make sure your device is actually powered on and sending a signal before you dive into the menu. Also, if you’re already in "Game Mode," the TV sometimes locks these settings because it’s already trying to optimize the signal.
The Gaming Connection: 120Hz and VRR
If you’re a gamer, this isn't optional. It’s mandatory.
A lot of people think that just because they have an HDMI 2.1 cable, the TV will magically do the rest. Nope. On many Samsung TVs, specifically older QLEDs like the Q70T, only HDMI Port 4 (the one with the little controller icon) fully supports the 120Hz bandwidth. If you plug into Port 1 and don’t turn on Samsung Input Signal Plus, you’re going to be capped at 4K 60Hz or even 1080p.
When this feature is active, it unlocks:
- 4K at 120Hz: Essential for smooth motion in shooters like Call of Duty or Halo.
- VRR (Variable Refresh Rate): Stops that ugly screen tearing when the framerate dips.
- HDR (High Dynamic Range): This is the big one. Without Input Signal Plus, your PS5 will literally tell you "HDR not supported."
Interestingly, some users on Reddit and the Samsung Community forums have reported that Input Signal Plus can occasionally cause "black screen" flickers. This usually happens if your HDMI cable isn't actually "Ultra High Speed" (48Gbps). If you turn the setting on and your screen starts blinking like a strobe light, your cable is the weak link, not the TV.
Apple TV 4K and the "No Signal" Headache
It’s not just for gamers. If you’re using an Apple TV 4K or a high-end Shield TV, you might notice that 4K Dolby Vision (or HDR10+ in Samsung's case) looks a bit muted.
Apple TV is notorious for doing a "handshake" test. If Samsung Input Signal Plus is off, the Apple TV won't even show you the option for "4K HDR" in its internal settings. It’ll default to "4K SDR." Turning on the setting on your Samsung TV suddenly makes those vibrant colors pop.
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However, there is a weird quirk. Some older 4K receivers don’t play nice with this. If your setup goes Apple TV -> Receiver -> Samsung TV, and the receiver doesn't support the latest passthrough specs, turning on Input Signal Plus might actually break the connection entirely, leaving you with a "No Signal" message. In that case, you’re better off plugging the Apple TV directly into the TV and using eARC for audio.
Real-world Troubleshooting: When things go sideways
I've spent way too much time helping friends fix their "broken" TVs only to find it was this one setting. But sometimes, enabling it creates new problems.
For instance, the Samsung S95C and other models with the "One Connect Box" have had documented issues with signal dropouts when Input Signal Plus is pushed to the limit (like 4K 144Hz from a PC). If you’re getting intermittent blackouts, try lowering your PC's refresh rate to 120Hz or even 60Hz just to see if it stabilizes.
Also, dust is a real signal killer. If you're pushing the 48Gbps bandwidth that Input Signal Plus allows, even a tiny bit of grime in the HDMI port can cause data packets to drop. Use some compressed air. It sounds low-tech, but it works.
Actionable Steps for Your Setup
Don't just leave your TV on the factory defaults. If you want the picture quality you actually paid for, follow this checklist:
- Audit your cables: Ensure any cable connected to a console or PC is labeled "Ultra High Speed." If it’s just a generic "High Speed" cable from five years ago, it will fail when you turn on Input Signal Plus.
- Pick the right port: On newer Samsung TVs (2024–2026), all ports are usually HDMI 2.1. But on older sets, look for the "Game" icon or the "120Hz" label.
- Enable the toggle: Go to Connection > External Device Manager > Input Signal Plus and flip the switch for your active ports.
- Verify on the device: Check your Xbox, PS5, or PC settings. If "HDR" or "High Frame Rate" was greyed out before, it should now be selectable.
- Check for firmware updates: Samsung frequently releases patches that improve the stability of high-bandwidth signals. If you're getting flickers, check the Support menu for an update.
Samsung Input Signal Plus is basically the "Turbo" button for your HDMI ports. It’s the difference between a standard image and a true "next-gen" experience. If you’ve been looking at your screen and thinking it could look just a little bit better, this is almost certainly the reason why.