Samsung Odyssey G4B LS25BG400EU Gaming Monitor Review UK 2026

I've spent a lot of time in front of monitors. Calibrating them, testing them, arguing about them with people on the internet at midnight. And the one thing I keep coming back to is this: the monitor you choose isn't just a purchase, it's something you're going to stare at for potentially thousands of hours over its lifetime. Get it wrong and every gaming session, every late-night work sprint, every film you watch is just slightly worse than it should be. That's not dramatic. That's just the reality of living with a bad panel.

So when Samsung sent over the Odyssey G4B for testing, I was genuinely curious. The 240Hz IPS promise at a mid-range price point is exactly the kind of spec sheet that sounds brilliant on paper but often disappoints in practice. I've been burned by "1ms" claims before. I've seen IPS panels that look washed out, VA panels with crushing black smear, and HDR badges that are basically fiction. My job is to find out whether the G4B is the real deal or just clever marketing dressed up in a sleek chassis.

I ran this monitor through about a month of daily use, covering competitive gaming, content work, and long evening sessions. Here's what I found.

The panel covers 99% of the sRGB colour space and Samsung quotes a peak brightness of 350 nits in SDR mode. It supports HDR10 and carries an HDR400 certification, which tells you quite a lot about the real-world HDR experience before you've even plugged it in. Connectivity is kept fairly minimal: one DisplayPort 1.2 and two HDMI 2.0 ports, plus a 3.5mm headphone jack. No USB hub, no USB-C. The stand offers tilt adjustment only, which is worth knowing upfront if you need height or pivot flexibility.

On paper, this is a monitor aimed squarely at competitive gamers who want the highest possible refresh rate without spending OLED money. The 25-inch size and 1080p resolution combination is a deliberate choice for esports use, where pixel density per frame matters less than raw frame delivery speed. At this price point in the mid-range bracket, it's competing with a fairly crowded field, but the Samsung name and 240Hz IPS combination give it a reasonable starting position.

Viewing angles are, as expected from IPS, excellent. You can sit off to the side at a fairly steep angle and the image holds up well without the colour shift you'd get from a TN panel or the contrast crush you'd see on VA. For a desk setup where you might have a friend watching alongside you, or where you're not always perfectly centred, this matters more than people give it credit for. The G4B's panel maintains consistent colour reproduction across a wide horizontal and vertical range, which I confirmed by moving around during testing rather than just sitting in the sweet spot.

The native contrast ratio sits at 1000:1, which is typical for IPS and noticeably lower than the 3000:1 or higher you'd get from a VA panel. In practice, this means blacks look more like very dark grey in a dim room. It's not awful, but if you're coming from a VA monitor, the difference will be immediately obvious. IPS glow is present in the corners when displaying dark content, particularly noticeable during the opening of dark-themed games or films. It's not the worst I've seen on an IPS panel, but it's there. IPS technology fundamentally trades contrast depth for colour accuracy and viewing angles, and the G4B is no exception to that rule.

The anti-glare coating on the G4B is a standard matte finish, which does a decent job of diffusing reflections in a normally lit room. I tested it next to a window during the day and while there was some haze from the coating itself, it was far more usable than a glossy panel would be in the same conditions. The coating does add a very slight graininess to the image that some people find distracting, particularly on white backgrounds. It's subtle, but worth mentioning for anyone who's sensitive to that kind of thing.

Brightness uniformity across the panel was good during my testing. I ran a full-screen grey uniformity test and found no major hotspots or dark corners that would indicate backlight bleed issues. There was a very slight brightening toward the centre compared to the edges, but nothing that would be visible during normal use. Samsung's quality control on this seems solid, though as always with LCD panels, there's unit-to-unit variation. The 350-nit peak brightness is adequate for most indoor environments, though in a very bright room or near a window, you might find yourself wishing for a bit more headroom.

The AMD FreeSync Premium certification means this monitor supports variable refresh rate from 48Hz up to 240Hz with Low Framerate Compensation (LFC) active. LFC kicks in when your frame rate drops below the minimum VRR threshold, doubling or tripling frames to keep the sync working rather than letting you fall out of the adaptive sync range into tearing territory. For competitive gaming where you're typically pushing high frame rates anyway, this matters less, but it's a useful safety net for less demanding titles or older hardware.

The G-Sync Compatible validation is worth understanding properly. This isn't the same as a full G-Sync module, which includes dedicated hardware for additional features and stricter certification. What G-Sync Compatible means is that Nvidia has tested this panel and confirmed it works reliably with their adaptive sync implementation without major artefacts. In practice, I ran it with both an AMD RX 7600 and an Nvidia RTX 4060 during testing, and the adaptive sync behaviour was clean on both. No flickering, no obvious sync drop-outs, no visual weirdness at the frame rate transitions. It just works. Nvidia's G-Sync Compatible programme has become a reliable indicator of real-world VRR quality, and the G4B passes that test comfortably.

That said, the G4B's motion performance is genuinely impressive for an IPS panel at this price. I tested it extensively in dark scenes in games like Halo Infinite and Doom Eternal, looking specifically for the kind of trailing and ghosting that can make fast movement look smeared. With the overdrive set to the middle "Faster" setting (rather than the maximum "Fastest"), ghosting was minimal and the image stayed clean through rapid camera movements. The maximum overdrive setting does introduce some inverse ghosting, where you get a bright halo ahead of moving objects. It's visible if you're looking for it, particularly on dark backgrounds. I'd recommend sticking with the middle overdrive setting for most use.

For competitive gaming, the motion clarity on the G4B is among the better IPS experiences I've had at this price point. The combination of 240Hz and the fast IPS panel means that even without MPRT (Moving Picture Response Time) backlight strobing, the motion looks clean. If you're coming from a 60Hz or even 144Hz panel, the improvement will be dramatic. The 1ms marketing number is still a bit cheeky, but the underlying performance backs up the intent behind it. This is a fast panel. Just not magically 1ms fast.

After a quick calibration using a colorimeter, I got the average Delta E down to around 1.4, which is genuinely good. The panel has the underlying quality to perform well; it just needs a bit of work to get there. For gaming, the out-of-box calibration is fine. For any serious colour work, photo editing, or video production, you'd want to calibrate it properly. The G4B doesn't cover DCI-P3 or Adobe RGB to any meaningful extent, so if wide-gamut colour work is your priority, this isn't the right tool. It's built for sRGB, and within that space it performs well.

The colour temperature out of the box runs slightly warm, which is common with Samsung panels. The default preset tends to push things toward a yellowish-white rather than a neutral D65 white point. This is easy to correct in the OSD or through calibration software, but it's worth knowing if you're the kind of person who notices these things immediately. The OSD colour controls are reasonably flexible, with separate RGB gain adjustments and several preset modes including a dedicated "FPS" mode that boosts visibility in dark areas. I found the standard sRGB mode the most accurate starting point for calibration work.

This isn't Samsung's fault specifically. It's a fundamental limitation of the HDR400 tier and single-zone backlighting. Real HDR requires either a very high peak brightness (1000+ nits) to create genuine contrast between bright and dark areas simultaneously, or local dimming to selectively control brightness across different zones of the panel. The G4B has neither. For comparison, monitors with meaningful HDR performance typically carry HDR600 or HDR1000 certification and use mini-LED backlighting with many dimming zones, or they're OLED panels where each pixel controls its own light output.

My recommendation is to leave HDR disabled on the G4B for most content. The SDR image, properly calibrated, looks significantly better than the HDR mode for gaming and general use. If a specific game or application forces HDR, the experience isn't terrible, but it's not the transformative visual upgrade that HDR is supposed to represent. Don't buy this monitor expecting HDR to be a feature. It's a spec sheet checkbox, not a real capability at this tier. The good news is that this is true of almost every monitor in this price bracket, so it's not a reason to avoid the G4B specifically.

Peak SDR brightness of 350 nits is adequate for most UK home environments. I tested it in a room with a window to my left during afternoon testing sessions, and while there was some washout from ambient light, it remained usable. In a properly controlled gaming environment with the lights down, 350 nits is more than enough. I wouldn't want to use it as a secondary display in a very bright office environment without some window treatment, but for a gaming setup, it's fine. The brightness uniformity I mentioned earlier helps here too, as consistent backlight delivery means you're getting the full 350 nits across the whole panel rather than just in the centre.

One thing I noticed during extended testing was that the panel maintains its brightness well over time without significant dimming during long sessions. Some budget panels will throttle brightness after extended periods to manage heat, but the G4B stayed consistent throughout multi-hour gaming sessions. The backlight also doesn't exhibit any obvious PWM flicker at typical brightness settings, which is good news for people who are sensitive to that kind of thing. Samsung uses DC dimming at higher brightness levels, though at very low brightness settings there may be some PWM activity. For most users at normal brightness, this won't be an issue.

The build quality of the chassis itself is decent for the price. The plastic doesn't feel premium, but it doesn't feel cheap either. The bezels are reasonably thin on three sides, with a slightly thicker bottom bezel housing the Samsung branding. The overall aesthetic is clean and understated, without the aggressive RGB lighting and angular styling that some gaming monitors go for. Personally, I prefer this approach. The G4B looks like a proper monitor rather than a prop from a sci-fi film, which means it works in a wider range of setups.

The OSD controls are physical buttons on the back-right of the panel, which is a slightly awkward placement but functional once you've memorised the layout. There's no joystick navigation, which would be more intuitive, but the button layout is logical enough. The OSD itself is well-organised with clear categories for picture settings, colour, and gaming-specific options like the overdrive control and the aim point overlay. The stand footprint is relatively compact, which is useful if desk space is at a premium. Overall, the build is solid without being exceptional. It does the job.

There's no USB-C port, which isn't surprising at this price point but worth noting if you were hoping to use it with a laptop via a single cable. There's also no USB hub, so if you need to connect peripherals through the monitor, you're out of luck. The 3.5mm headphone jack is a welcome inclusion for passing audio through from the DisplayPort or HDMI connection, though the G4B has no built-in speakers. That's fine for a gaming monitor at this level; built-in speakers on monitors in this bracket are rarely worth using anyway.

• 1x DisplayPort 1.2
• 2x HDMI 2.0
• 1x 3.5mm headphone output
• No USB hub
• No USB-C

The cable management on the stand is basic. There's a small routing gap in the stand neck that lets you thread cables through to keep things tidy, but it's not the most elegant solution. If you're using a monitor arm, this becomes irrelevant. The power supply is internal, which means no external power brick to deal with, and the power cable connection is a standard IEC C14 socket at the back of the panel. All fairly standard stuff, but worth confirming for anyone planning a clean cable setup.

Where the G4B has an edge over some competitors is in Samsung's panel quality consistency and the brand's after-sales support. Samsung's dead pixel policy and warranty support in the UK is generally solid, which matters when you're buying a display where a single stuck pixel in the wrong place can be genuinely annoying. The G4B also benefits from Samsung's experience with fast IPS panels, and the motion performance reflects that. Some cheaper 240Hz IPS panels achieve the refresh rate but have worse overdrive tuning, leading to more visible inverse ghosting at the maximum setting.

The honest comparison to make is also against stepping up to 1440p. For a similar or slightly higher outlay, you can get a 1440p 165Hz or 144Hz IPS panel that offers significantly better image quality for general use, productivity, and visually rich games. If competitive esports gaming is your primary use case and you're regularly hitting 200+ FPS in your titles of choice, the G4B's 240Hz at 1080p makes sense. If you're a more general gamer who plays a mix of competitive and single-player titles, the extra resolution of a 1440p panel might serve you better overall.

The complaints that come up repeatedly are predictable given the spec sheet. The stand's lack of height adjustment is the most common frustration, with multiple reviewers noting they had to buy a monitor arm or improvise a solution. A handful of buyers mention IPS glow in dark scenes, which is a panel technology limitation rather than a defect, but it's worth knowing about if you're sensitive to it. There are also occasional mentions of the HDR mode being underwhelming, which aligns with my own testing. The buyers who seem most satisfied are those who bought it specifically for competitive gaming and went in with realistic expectations about what a mid-range 1080p monitor can and can't do.

A few reviews mention dead pixel issues, which is always a risk with LCD panels. Amazon's return policy makes this manageable, as you can check for dead pixels immediately and return if needed. The overall picture from buyer feedback is of a monitor that does exactly what it promises for its target audience, with the limitations being inherent to the technology tier rather than specific manufacturing problems. The high review count and strong average rating suggest that most buyers are getting what they paid for, which is reassuring.

Where the value calculation gets more complicated is if you're a general gamer or someone who uses their monitor for a mix of gaming and other tasks. At this price point, you could alternatively get a 1440p 144Hz IPS monitor that would offer a noticeably better experience for productivity, content consumption, and visually rich single-player games, while still being more than fast enough for most gaming. The 240Hz advantage only really pays off if you're consistently generating frame rates above 144 in your most-played titles. If you're playing demanding AAA games at 60-100 FPS, the extra refresh rate headroom is largely wasted.

That said, for its intended purpose, the G4B is priced fairly. You're not paying a premium for features you don't need, and the core gaming performance is delivered without compromise. The build quality is appropriate for the price, the panel quality is solid, and the Samsung warranty provides reasonable peace of mind. If 240Hz competitive gaming is genuinely your priority, the value here is real. Just be honest with yourself about whether that's actually what you need before committing.

The limitations are real but mostly predictable. The stand is frustrating, the HDR is checkbox-level, and the 1080p resolution means it's not the right choice for productivity-heavy users or people who want the best possible image quality for single-player games. The 1ms response time claim is marketing shorthand rather than literal truth, though the actual motion performance is still very good. None of these are deal-breakers for the right buyer, but they're worth understanding before you hand over your money.

My overall score is 7.5 out of 10. It's a genuinely good monitor for competitive gaming at a fair mid-range price, held back from a higher score by the stand limitations, the checkbox HDR, and the resolution compromise that makes it less versatile than some alternatives. If you're a competitive gamer who knows what 240Hz means and why you want it, the G4B delivers. If you're less sure about your use case, consider whether a 1440p alternative might serve you better in the long run.