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Results: Brightness and Contrast

Overlord Tempest X270OC, 27" 120 Hz IPS Gaming Monitor Review

The X270OC would not accept a signal from our AccuPel signal generator, so all measurements were taken with Overlord's monitor connected to a PC via DVI. Patterns were rendered by CalPC Client 3. We took default readings with all look-up tables turned off to be sure we were recording raw values. After creating a custom LUT with CalPC, we measured the results.


Before calibrating any panel, we measure zero and 100-percent signals at both ends of the brightness range. This shows us how contrast is affected at the extremes of a monitor's luminance capability. The X270OC does not have a contrast control, so signal clipping is not an issue. Light output can only be modulated using brightness, which affects the backlight level.

Today’s comparison group consists of the high-refresh gaming monitors we’ve reviewed, plus Asus' value-oriented 4K display, the PB287Q. I'm also adding a typical 27-inch IPS screen, NEC’s EA274WMi.

Overlord rates the X270OC at 380 cd/m2. The most light we measured was 258.5601 cd/m2, though. It's probable that Overlord is citing the panel part's specification. Typical gameplay doesn't require a super-bright display, so this shouldn't be a tremendous issue.

A low maximum black level beats the TN-based panels in our comparison. When I checked our database, I found that Overlord's X270OC bests almost all of the other IPS screens as well.

NEC's screen trumps the Tempest only because of its higher white level. The same is true of this group's other models. Among IPS displays, however, Overlord is at or near the top for maximum contrast.

We believe 50 cd/m2 is a practical minimum standard for screen brightness. Any lower and you risk eyestrain and fatigue. The X270OC bottoms out at 83.0312 cd/m2, which is a great light level for playing games in total darkness. As you’ll see below, black levels and contrast also hold up extremely well.

A last-place result in this test isn't a big deal when you’re talking about such low black levels. If all of the monitors were lined up in a row, it'd be a challenge to pick the darkest one.

The Tempest’s contrast remains super-consistent at all brightness levels. We’re seeing a positive trend towards better contrast performance from both TN and IPS screens. That Overlord can offer results this good with a $450 display is impressive.

After Calibration

Since we consider 200 cd/m2 to be an ideal point for peak output, we calibrate all of our test monitors to that value. In a room with some ambient light (like an office), this brightness level provides a sharp, punchy image with maximum detail and minimum eye fatigue. On many monitors, it’s also the sweet spot for gamma and grayscale tracking, which we'll look at on the next page. Many professionals prefer a 120 cd/m2 calibration in darker rooms. We find that makes little to no difference on the calibrated black level and contrast measurements.

We set the maximum output level using the X270OC’s only available adjustment, brightness. Our results reflect the color and gamma adjustments made by the CalPC-generated LUT.

A calibrated black level result of .218 cd/m2 is excellent. Typically, monitors take a small hit after we adjust them. But not the Tempest. Perhaps this is attributable to the finer control possible with a software LUT. Most displays employ OSD controls that aren't as precise.

An improvement like this makes calibration worth the time and expense, though.

The X270OC posts incredibly consistent contrast results. Whether you calibrate or not, and regardless of backlight setting, the contrast ratio is always around 925 to 1.

ANSI Contrast Ratio

Another important measure of contrast is ANSI. To perform this test, a checkerboard pattern of sixteen zero and 100-percent squares is measured. We get a somewhat more real-world metric than on/off measurements because we're testing the display’s ability to simultaneously maintain both low black and full white levels, plus factoring in screen uniformity. The average of the eight full-white measurements is divided by the average of the eight full-black measurements to arrive at the ANSI result.

The Tempest loses no ground in the ANSI contrast test. Since screen uniformity is a factor, some samples will measure better or worse than ours. Even still, it's impressive to come across such strong build quality from a low-priced IPS display.

Display all 109 comments.
  • 1 Hide
    oudmaster , July 17, 2014 12:54 AM
    the price is interesting with these specs !
    any idea if there will be a similar monitor spec but 4k resolution ?

  • -5 Hide
    oudmaster , July 17, 2014 12:54 AM
    the price is interesting with these specs !
    any idea if there will be a similar monitor spec but 4k resolution ?

  • -3 Hide
    oudmaster , July 17, 2014 12:55 AM

  • 4 Hide
    wtfxxxgp , July 17, 2014 2:08 AM
    Crickey me...this is a monitor of note it seems! At that price point, I find it incredible. Well done to Overlord! The only issue I have now is... will the price increase as a result of all the buzz this will generate? This is probably going to be my next monitor, depending on exchange rates...
  • -5 Hide
    Shneiky , July 17, 2014 2:12 AM
    4K at 120 MHz? Not in the next 5 years.
  • 2 Hide
    Swiperd3 , July 17, 2014 3:23 AM
    Driving QHD to 120 FPS at the max graphics detail is sure as hell will require A LOT of horsepower. Will TOP-SLI/CF-x2 be enough for modern FPS games?
  • 1 Hide
    Traciatim , July 17, 2014 4:04 AM
    Wow, you get this with one of the variable sync techs and you have yourself one fantastic monitor.
  • 0 Hide
    waxdart , July 17, 2014 4:11 AM
    16:9 :( 
  • 5 Hide
    envy14tpe , July 17, 2014 4:37 AM
    Thank you Thank you Thank you. I've been dying to see a review on this monitor.
  • 1 Hide
    Reaver192 , July 17, 2014 4:44 AM
    Yeah, I've been waiting fir this for too long. I wanted one of these months ago but they have been out of stock. Such a sweet deal
  • 5 Hide
    avatar_raq , July 17, 2014 5:27 AM
    This is the holy grail of PC monitors, if only it comes with 120 Hz guaranteed out of the box.
  • 2 Hide
    yogalD , July 17, 2014 5:34 AM
    I wish it had a strobe backlight though, that would make it perfect
  • 5 Hide
    Durandul , July 17, 2014 6:17 AM
    If it had an option for Display port, that would have been almost perfect. That being said, I use DVI anyway, so who am I to complain.
  • 2 Hide
    MonsterCookie , July 17, 2014 6:50 AM
    This is already a step at the good direction. Even the price in $ looks decent.
    Question is how much will this cost here in Europe.

    Also, now make the same thing happen in a 30" format with 2560x1600 resolution, and than I am definitely opening my wallet.
  • 2 Hide
    mapesdhs , July 17, 2014 7:14 AM

    MonsterCookie, alas I doubt that will happen. A few years ago, 1440 and 1600
    height monitors were priced basically the same, ie. expensive. Back then, top-end
    GPU reviews tended to use 2560x1600 as a typical max res test for gaming. But
    then buying patterns evolved, the usual feedback between pricing and demand,
    people tended to opt more and more for 1440 displays instead. As a result, when
    I wanted to get a 1600 IPS a while ago, I was amazed to find 1600 hieght displays
    were about 4X more expensive than 1440 IPS models.

    Presumably it suits the industry to home in on a more typical standard, and for
    the moment, beyond HD, 2560x1440 seems to be it. Very unlikely the industry has
    any interest in pushing 1600 height to the masses, so probably the next main step
    up will be to 4K, or as I wish they'd call it instead, quad-HD.


  • 1 Hide
    ubercake , July 17, 2014 7:14 AM
    The specs look goood, but the key is they don't guarantee 120Hz for all OC monitors:

    It's like hoping you'll get an i7 that will have a stable OC to 4.5Ghz 24/7. It's the luck of the draw.
    I don't much like putting my money on hope. If they did have a guarantee or just sold a monitor that shipped to my house with 120Hz capability, I'd be more likely to hand over my cash.

    You know darn well they make sure the review site is getting a good one.
  • 1 Hide
    daglesj , July 17, 2014 7:29 AM
    So does it work fine at say 90Hz and if so is that an improvement?
  • 1 Hide
    npyrhone , July 17, 2014 7:42 AM
    Thanks a million for the review! This will be next monitor. Hallelujah! Lacking a decent non-TN gaming panel, I've played with a pro 24" CRT for all these years.
  • 2 Hide
    npyrhone , July 17, 2014 7:46 AM
    A few answers and corrections concerning ideas thrown around in this thread:

    1) Yes, This works perfectly at 90Hz. Yes, it is a great improvement. Much greater improvement is 60->90 than 90->120.

    2) All monitors are from this day to the future to come 16:9. So, its useless to fancy 16:10 monitors anymore, they wont be coming ever again.

    3) 4K 120Hz gaming monitors wont be coming, either. At least not in the foreseeable future.

    4) Overclocking this is not luck of the draw. They all come at least 96Hz, and the great majority work 120Hz.

    5) The lack of displayport etc is what helps keeping input lag low.
  • 9 Hide
    rishiswaz , July 17, 2014 8:11 AM
    I wonder why they don't just have another model with cherry-picked panels that they ship at 120 out of the box
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