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Measurement and Calibration Methodology: How We Test

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

To measure and calibrate monitors, we use an i1Pro spectrophotometer, a SpectraCal C6 colorimeter, and version 5.2.0.1374 of SpectraCal’s CalMAN software.

The i1Pro is very accurate and consistent measuring color on all types of displays, regardless of the backlight technology used. When we just need a luminance value, the C6 works better, especially in low light.

For patterns, we employ AccuPel DVG-5000 and DVDO AVLab TPG video signal generators. This approach removes video cards and drivers from the signal chain, allowing the display to receive true reference patterns. Connections are made via HDMI.

The AccuPel DVG-5000 is capable of generating all types of video signals at any resolution and refresh rate up to 1920x1080 at 60 Hz. It can also display motion patterns to evaluate a monitor's video processing capabilities, with 3D patterns available in every format. This allows us to measure color and grayscale performance, crosstalk, and ghosting in 3D content via the 3D glasses.

The DVDO generator is a new addition to our lab. It supports resolutions up to 4096x2160. We’re using it to verify the proper signal handling of QHD and UHD displays.

The i1Pro or C6 is placed at the center of the screen (unless we’re measuring uniformity) and sealed against it to block out any ambient light. The AccuPel pattern generator (bottom-left) is controlled via USB by CalMAN, which is running on the Dell XPS laptop on the right.

Our version of CalMAN Ultimate allows me to design all of the screens and workflows to best suit the purpose at hand. To that end, I’ve created a display review workflow from scratch. This way, we can be sure and collect all the necessary data with a concise and efficient set of measurements.

The charts show us the RGB levels, gamma response, and Delta E error for every brightness point from zero to 100 percent. In the table, we get raw data for each measurement. And the area in the upper-left tells us luminance, average gamma, Delta E, and contrast ratio. The individual charts can be copied to the Windows clipboard to easily create graphics for our reviews.

Every primary and secondary color is measured at 20-, 40-, 60-, 80-, and 100-percent saturation. The color saturation level is simply the distance from the white point on the CIE chart. You can see the targets moving out from white in a straight line. The further a point is from center, the greater the saturation until you hit 100 percent at the edge of the gamut triangle. This shows us the display’s response at a cross-section of color points. Many monitors score well when only the 100-percent saturations are measured. Hitting the targets at the lower saturations is more difficult, and factors into our average Delta E value (which explains why our Delta E values are sometimes higher than those reported by other publications).

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 ?

    thanks,
  • -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 ?

    thanks,
  • -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.

    Ian.

  • 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:
    http://overlordcomputer.com/blogs/news/7384176-the-overclock-overview

    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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