Most light bar reviews test brightness at the center of the desk, hand you a spec sheet, and move on. That works fine if your monitor sits perfectly centered above your keyboard on a flat rectangle of a desk. Mine does not. After three weeks testing both bars side by side on an L-desk with my monitor shifted about 15cm to the right of center, I found that desk geometry matters more than any spec on the box.
Here is what I actually measured, and what those numbers mean for your setup.
The Thing Nobody Explains About Asymmetric Illumination
Both the BenQ ScreenBar and the Yeelight Monitor Light Bar use asymmetric illumination. That phrase shows up in marketing copy constantly, but I have never seen a review actually explain what it means in practice.
The light beam projects at roughly 25 degrees below horizontal, angling down and forward toward your keyboard and desk rather than casting light in all directions. The reason: your monitor screen sits directly behind the bar. A symmetrical beam would bounce off the screen and create glare. The asymmetric angle sends light forward and down, keeping your screen out of the beam path entirely.
Smart design. The problem is what happens to that angled beam when your keyboard is not centered under the bar.
Because the beam projects forward at an angle, the coverage footprint is wider at the far edge of your desk than near the monitor. When your keyboard is centered, you are in the sweet spot. Shift it to the side and you move into the edge of that asymmetric cone, where lux output drops off faster than you would expect.
I measured this with a light meter at keyboard height, 5cm above the desk surface, at the position where my hands rest while typing.
BenQ ScreenBar (450mm wide, 530g, ~$99 on Amazon):
- Keyboard centered under monitor: 280 lux
- Keyboard shifted 10cm left of center: 190 lux
- Keyboard shifted 20cm left of center: 115 lux
Yeelight LED Monitor Light Bar (~$40 on Amazon):
- Keyboard centered under monitor: 210 lux
- Keyboard shifted 10cm left of center: 140 lux
- Keyboard shifted 20cm left of center: 80 lux
The BenQ holds its output about 30-40% better at the edges. On a standard centered desk, both bars deliver adequate keyboard illumination. The gap only opens when your geometry is not ideal. If you are running an L-desk, a corner desk, or a multi-monitor setup where one screen is off-center, that gap matters.
BenQ ScreenBar: The Specs
The standard ScreenBar is 450 x 90 x 92mm and weighs 530g. It clips to monitor bezels 1 to 1.3cm thick. Touch controls sit on the top face: hold to adjust brightness, swipe to shift color temperature through 8 steps from 2700K (warm amber) to 6500K (cool daylight).
Power draw maxes at 5W through a standard USB-A port. CRI (color rendering index) is rated at 95+, which is genuinely high. Paper looks like paper under it. If you work with printed reference materials, physical fabric or paint samples, or do any color-sensitive work at your desk, that CRI rating translates into real accuracy.
BenQ specs the coverage at 500 lux across a 60cm x 30cm footprint, with a peak of 930 lux at center. My keyboard-height measurements ran lower, which is expected since manufacturers test at center desk height. The coverage area claim checks out on a centered setup.
The auto-dimming sensor on the front face reads ambient light and adjusts the bar output automatically. In a stable room it works fine. In a room with shifting natural light through windows it becomes slightly aggressive, and I found myself toggling it off by midday.
BenQ ScreenBar Plus: Same Bar, Better Control
The ScreenBar Plus runs about $149 on Amazon and uses the same 450mm lamp head with identical light output: 930 lux center, 500 lux across the same 60x30cm footprint. The bar itself is the same. What you are paying for is the desktop dial controller.
The dial is a 74 x 74 x 32mm puck that sits on your desk. Turn it to adjust brightness. Press and turn to shift color temperature. Double-press to toggle the auto-dimmer. The total rig weighs 680g versus 530g for the standard model.
If you adjust your lighting frequently through the day, the dial earns its price. I shift between warmer light for morning email and cooler light for focused afternoon writing, and reaching up to touch-controls on the bar itself gets old fast. The dial removes that friction.
If you set your light once at setup and leave it, save the $50 and buy the standard.
Yeelight LED Monitor Light Bar: Where It Wins and Where It Does Not
The Yeelight YLTD001 runs about $40 and brings a noticeably different feature set. It uses 80 white LEDs on the front face plus 40 RGB LEDs on the rear. The RGB backlight is Razer Chroma compatible, useful for gaming setups or anyone who wants ambient bias lighting behind the monitor.
Power draw is 10W versus BenQ at 5W. The mount uses a magnetic connection that makes removal and reinstallation faster than BenQ’s clip mechanism. The bracket can pivot up to 25 degrees, which helps: if your keyboard is slightly off-center, you can angle the beam toward it rather than leaving it pointed straight forward.
CRI is Ra90 versus BenQ’s 95+. Colors look slightly flatter under the Yeelight, particularly with printed materials. For pure screen work, you will not notice.
Where the Yeelight falls short: the lux drop-off at the edges is steeper than the BenQ. On a centered setup, 210 lux at keyboard height is adequate for typing and general work. At 20cm off-center, you are at 80 lux, which is borderline dim for sustained work sessions. The bracket pivot helps compensate partially, but it does not close the gap.
Head-to-Head: What Actually Matters
Light output quality: BenQ. CRI 95+ versus Ra90 is measurable and visible with physical materials. For pure screen work, both are adequate.
Off-center desk coverage: BenQ by a significant margin. At 20cm off-center, 115 lux versus 80 lux. If your desk is not a simple centered rectangle, the BenQ’s more consistent coverage pattern is the reason to pay more.
Daily controls: ScreenBar Plus wins clearly. The dial is the best light control interface at this price. Standard ScreenBar touch controls are functional but awkward to reach. Yeelight’s remote adds another item to manage on your desk.
Ambient and gaming lighting: Yeelight wins. The RGB rear glow is something BenQ does not offer at any price.
Price: Yeelight at $40 is strong value on a standard centered desk.
Mount flexibility: Yeelight’s magnetic mount and pivoting bracket score points for flexibility, though the weaker edge coverage undercuts that advantage on offset setups.
Who Should Buy Which
Get the BenQ ScreenBar Plus ($149) if you work at a corner desk, L-desk, or any setup where your keyboard sits more than 10cm off-center from your monitor. The coverage pattern is more forgiving, and the dial controller makes frequent adjustments easy. This is the recommendation I give to most serious home office setups.
Get the BenQ ScreenBar standard ($99) if your desk is a standard rectangle with monitor centered above keyboard and you do not adjust light settings throughout the day. You get 95+ CRI and solid edge coverage without paying for the dial.
Get the Yeelight ($40) if you have a standard centered desk, are watching your budget, or specifically want RGB rear lighting for a gaming setup. At that price it over-delivers for what it is.
Do not buy the Yeelight if you work at a corner desk or L-desk. The light falloff at the keyboard edges becomes a real frustration on offset setups.
The Number Worth Remembering
At 20cm off-center, the BenQ ScreenBar delivers 115 lux at keyboard height. The Yeelight delivers 80 lux. The industry recommendation for computer tasks is 300-500 lux at the work surface. Both bars fall below that target on offset setups, but the BenQ gets you closer.
On a centered desk, both bars hit 200+ lux at keyboard height, adequate for typing and general work when room ambient light supplements the bar.
The BenQ costs $59 more than the Yeelight. If your desk is perfectly symmetrical and centered, that premium is hard to justify. If it is not, it is the difference between adequate light and noticeably dim light on the half of your keyboard that gets used most.
Buy for your actual desk, not the idealized version of it.
