BenQ XL2720Z overclocked to 220Hz and 250Hz [SUCCESS!]

[loopy750]

It's quite simple, set the following timings:

Refresh rate: 220Hz
Active pixels: 1920, 1080
Front porch: 24, 3
Sync width: 32, 5
Total pixels: 1984*, 1094*
Polarity: Positive, Positive (unsure if changing this has any effect)

* Total pixel settings required may vary depending on GPU & cable used. If 1984/1094 introduces frameskipping, experiment with other values, such as 2005/1088 (while confirming 8-bit colour depth mode is still in effect when running at 165Hz.)

When you see the "Out of Range!" message, select one of the saved modes on the controller (1, 2, or 3), and the monitor reappears with the overclocked refresh rate.

It appears the 220Hz limit is due to the Pixel clock, at just under 480MHz, which is the DisplayPort limit for this monitor.

*insert disclaimer here about how this might reduce the life of your monitor*

Of course, Blur Reduction isn't as good as the VT 1500 tweak, but it's still quite reasonable. AMA Premium actually looks better than AMA High, and Strobe Utility settings are Persistence: 10, Crosstalk Area: 18.

My new daily driver is now 165Hz with the same timings, as this is the limit for 8-bit colour depth. I use 220Hz (6-bit colour depth) for gaming only.

[Falkentyne]

Are you sure this works?

Try this in a game that can run 220 FPS with vsync enabled, and you'll see the framerate completely messed up.
For proof, use ToastyX Custom Resolution Utility with these same settings.
It will remain out of range forever. Can you check in toastyX CRU?

The issue is that the Nvidia Control panel creates GPU scaled resolutions, not EDID overrides. So the monitor winds up running "240hz" reported on the desktop with 144hz actually sent to the monitor. People used similar settings to get 180hz on an XL2411Z, but framerate tests actually showed it was reporting 180hz but running at 144hz. ToastyX CRU simply gave a proper out of range error. This was only verified by framerate sync tests then trying ToastyX CRU, which never gave a signal.

[loopy750]

Hi Falkentyne

I'm 99% sure which is why I'm hoping someone with the same monitor and better testing methods can confirm.

I tested a game locked at 220Hz with VSYNC enabled and everything was fine. I tested CRU and that also worked, although the colours were a little messed up, so that wasn't working 100%, but it still appeared to be 220Hz. Going back to the Nvidia control panel overclock method, I recorded this video with my phone, which can record at 240FPS. This is the best I can do. It skips the odd frame here and there (that's the camera doing that, not the monitor), but apart from that it looks to be 220Hz. This is one second of the recording slowed down.. what do you make of it?

https://streamable.com/sxva6

Update -
The reason for the weird colours using CRU is YCbCr422 instead of RGB, and Limited instead of Full. Also using CRU I'm able to push it to 250Hz, but YCbCr422 is not very pleasant to look at.

However, now that I'm able to test 240Hz with a 240FPS camera, this confirms it's working as expected. Again, a one-second video slowed down: https://streamable.com/bzxpc

[Chief Blur Buster]

This is an authentic overclock; and Here's Why It's Possible

Range-unlocked gaming monitors with good electronics sometimes have unusually massive overclock headroom if hacks are found. 1ms TN panels are very overclockable if the electronics can keep up. This is how 480Hz was successfully achieved on Zisworks 4K 120Hz and also the laptop 60Hz->180Hz overclock.

4:1 to 8:1 overclock ratios on TN panels are not impossible with the right TCON/scaler/firmware engineering like Zisworks did, and a 100%-200% overclock on factory electronics is sometimes unexpectedly unlocked through software-only hacks. The problem is few people can do firmware hacking, but your hack doesn't even require a firmware hack -- just use the S-Switch.

"Out of Range" popups is like Intel clock-limited CPUs. There's nothing stopping Intel from unlocking their processors. Likewise, there is nothing stopping a monitor manufacturer from unlocking their monitors (or users from discovering a bug that bypasses the "Out of Range" popup Hz limiter).

The problem is hacking the "Out of Range" popups, either via firmware hacking or via undocumented override hacks -- apparently you're the first person to figure out a way to override an "Out of Range" message on BenQ ZOWIE monitors. It's a very difficult monitor-specific hack, but you found a simple way: The S-Switch controller!

The XL2720Z is a well engineered monitors electronically, very stable 144Hz, so I'm not surprised at all it had hidden overclock headroom all the way thru 240Hz. However, overriding the "Out of Range" limiter popup is almost impossible -- unless there's a bug (like the one you discovered) that bypasses the clock limiter (Hz limiter).

https://streamable.com/sxva6

Confirmed 220Hz

However, now that I'm able to test 240Hz with a 240FPS camera, this confirms it's working as expected. Again, a one-second video slowed down: https://streamable.com/bzxpc

Confirmed 240Hz

Oh wow -- genuine 240Hz overclock of an XL2720Z! I don't see any frame skipping.

Normally, you use a long-exposure single photograph, but a full-exposure 240fps high speed video (no shuttering between video frames)
also works -- however, some high speed cameras will frameskip because of how they do sensor scanouts. So high speed cameras aren't always ideal. Yours did full-exposure (no visible camera shutter closures between camera frames) so it was acceptable for this specific test. However, regardless, you've got a successful 220Hz/240Hz overclock!

Chief Blur Busters Confirms: This is an authentic overclock!

When you see the "Out of Range!" message, select one of the saved modes on the controller (1, 2, or 3), and the monitor reappears with the overclocked refresh rate.

That's The Easter Egg!!! -- Overriding "Out of Range" hack via external controller (S-Switch)

I will attempt the overclock on my very original BenQ XL2720Z and if it works, I'll post here that it even works on the earliest XL2720Zs too, since my unit comes from the first retail factory manufacturing run!

The quality is not as good as XL2740 or XL2546 but actually improves an XL2720Z. The XL2720Z is so good a 144Hz monitor that it is not cheaper than 240Hz monitors currently being sold, but if you already have an XL2720Z, you already have a ~240Hz-overclockable monitor sitting on your desk.

This is true Blur Busters flavored monitor hacking!

[Chief Blur Buster]

Confirmed.

Yup, it works! Authentic >200Hz Overclock.

On my old XL2720Z. On older firmware. Even firmware Version 2!

No frame skipping. Some scanlines definitely no frame skipping, and the ghosting actually decreases. Lag even feels lower.

1. Use DisplayPort
2. You need the S-Switch wedge as the "Out of Range" overrider.
3. You only need NVIDIA Control Panel (or ToastyX)
4. You can overclock your XL2720Z!

Calibration goes crappy and requires a re-calibration but the colors seems to look okay fine after a recalibration. Ghosting is actually not bad.

In NVIDIA Control Panel, 220Hz works, 240Hz fails for me with system lockup. Looks like the failure point will probably be between 200Hz-250Hz.

Occasionally 220Hz starts frameskipping (shows up as tiny microstutters in TestUFO), but pressing S-Switch a couple more times, fixes that right up. It certainly seems to be pushing the tolerances of the XL2720Z firmware. Especially if I switch modes often, it starts to frameskip. But pressing the S-Switch again a few more times, clears that up.

I'll break the news on blurbusters.com within 24 hours of further testing (risks, caveats, gotchas, etc).

[Chief Blur Buster]

WARNING: Be careful mixing 220Hz + Blur Reduction on older firmwares
Strobe Pulse Width (Persistence) above approximately 10 during a 220Hz overclock may cause the monitor to excessively overvoltage to backlight.

If you use Strobe Utility, configure Persistence to 5 before you overclock
I accidentally did, and caused the monitor to go bright and crash (it wouldn't turn back on again until I unplugged and connected HDMI first, turned off Blur Reduction, then plugged back in the DisplayPort); the XL2720Z uses a voltage-boosted strobe backlight. If you overclock the XL2720Z, be very careful using Blur Reduction mode. The voltage boosting is even more powerful at 220Hz, which means it could potentially cause Blur Reduction to burn out the backlight/electronics. So be careful... If you've ever done Strobe Utility tweaking before, launch it first at 144Hz, slide Persistence all the way down to around 5, and exist before you overclock your XL2720Z. Newer firmware will prevent too much voltage boosting, but the older firmwares didn't.

220Hz is low-risk if you don't use Blur Reduction
That said, 220Hz without blur reduction should be pretty harmless. Panel overclocking is generally harmless the am, but it is generating a potential risky bug with the Blur Reduction mode (at least with earlier firmware versions that doesn't have a protected voltage-boost).

Historically, panel overclocking generally hasn't caused permanent failures, so panel overclocking is generally pretty safe (usually safer than CPU overclocking too). Just be careful combining a voltage-boosted strobe backlight with a monitor overclock, since the firmware may accidentally boost the voltage too much at higher Hz.

I tested V2 firmware too, the 220Hz overclock works all the way back to V2.

Continuing more tests.

[Falkentyne]

WARNING: Be careful mixing 220Hz + Blur Reduction on older firmwares
Strobe Pulse Width (Persistence) above approximately 10 during a 220Hz overclock may cause the monitor to excessively overvoltage to backlight.

If you use Strobe Utility, configure Persistence to 5 before you overclock
I accidentally did, and caused the monitor to go bright and crash (it wouldn't turn back on again until I unplugged and connected HDMI first, turned off Blur Reduction, then plugged back in the DisplayPort); the XL2720Z uses a voltage-boosted strobe backlight. If you overclock the XL2720Z, be very careful using Blur Reduction mode. The voltage boosting is even more powerful at 220Hz, which means it could potentially cause Blur Reduction to burn out the backlight/electronics. So be careful... If you've ever done Strobe Utility tweaking before, launch it first at 144Hz, slide Persistence all the way down to around 5, and exist before you overclock your XL2720Z. Newer firmware will prevent too much voltage boosting, but the older firmwares didn't.

220Hz is low-risk if you don't use Blur Reduction
That said, 220Hz without blur reduction should be pretty harmless. Panel overclocking is generally harmless the am, but it is generating a potential risky bug with the Blur Reduction mode (at least with earlier firmware versions that doesn't have a protected voltage-boost).

Historically, panel overclocking generally hasn't caused permanent failures, so panel overclocking is generally pretty safe (usually safer than CPU overclocking too). Just be careful combining a voltage-boosted strobe backlight with a monitor overclock, since the firmware may accidentally boost the voltage too much at higher Hz.

I tested V2 firmware too, the 220Hz overclock works all the way back to V2.

Continuing more tests.

Chief, you tested newer firmware than V2?
How did newer firmware (like V5, V6, or V8) limit the voltage boosting?
Because I know that trying to enable single strobe at 50hz still shuts off the backlight at a too high strobe duty (persistence) and still fails to even enter strobe mode unless a custom VT is used (I think 1350, I forgot what Masterotaku said).

[loopy750]

Hey thanks Mr Chief, glad to see it get the Chief seal of approval - your passion for monitor technology is quite something

I'm quite surprised too this hadn't yet been discovered. Either that or someone had been keeping it to themselves all this time.

My technique for recording was basically using a Galaxy S8 camera, which is capable of 240FPS video, and then recording the Vegas Pro preview of the mp4 with Timecode on screen. It's amazing that just over 10 years ago we were lucky to have a phone capable of recording 240p video, and today we can do this.

250Hz was achieved by setting both vertical porch and sync to 1, as due to the DisplayPort bandwidth limit, that was really pushing it to the limit - maybe even slightly too far - and I wouldn't recommend it. Not to mention how much worse YCbCr422 looks compared to RGB, IMO, which is why I consider 220Hz the practical limit, and somewhere between 240-248Hz if YCbCr422 doesn't bother you.

It does make you wonder how much higher the monitor could potentially be overclocked if not bandwidth limited. And also how similar their 240Hz monitors might be if these are also capable of reaching such refresh rates.

In regards to any frameskipping, I think it's a similar case to the VT 1500 tweak, and just a matter of slightly adjusting the VT to find what works best for your monitor. In my case it's 1094.

A quick note on the V8 firmware, apart from the Zowie branding, I see no visible difference compared with BenQ's V5 firmware. But hey, that was overclocking is about... we learn by experimenting.

Another thing I noticed after entering the menu is the "Out of Range!" message will reappear even though it's not a blank screen. This means you can't really use the hidden AMA "Low" setting without having that message annoy you, but at these high refresh rates I'm not really seeing any benefit using it anyway.

I look forward to any new discoveries you may find.

[Falkentyne]

Confirmed.

Yup, it works! Authentic >200Hz Overclock.

On my old XL2720Z. On older firmware. Even firmware Version 2!

No frame skipping. Some scanlines definitely no frame skipping, and the ghosting actually decreases. Lag even feels lower.

1. Use DisplayPort
2. You need the S-Switch wedge as the "Out of Range" overrider.
3. You only need NVIDIA Control Panel (or ToastyX)
4. You can overclock your XL2720Z!

Calibration goes crappy and requires a re-calibration but the colors seems to look okay fine after a recalibration. Ghosting is actually not bad.

In NVIDIA Control Panel, 220Hz works, 240Hz fails for me with system lockup. Looks like the failure point will probably be between 200Hz-250Hz.

Occasionally 220Hz starts frameskipping (shows up as tiny microstutters in TestUFO), but pressing S-Switch a couple more times, fixes that right up. It certainly seems to be pushing the tolerances of the XL2720Z firmware. Especially if I switch modes often, it starts to frameskip. But pressing the S-Switch again a few more times, clears that up.

I'll break the news on blurbusters.com within 24 hours of further testing (risks, caveats, gotchas, etc).

Ok I tested this.
It doesn't work properly for 165 hz (a safe refresh rate that shouldn't go overboard on the voltage either). There is always microstuttering sometimes as much as 3 seconds apart (in the same interval). Going to test other Vertical Totals close to this value to see if it goes away (example, this has to be done at stuff like 85hz refreh rate with a VT tweak--VT 1501 works fine but other VT's in the 1497-1502 range will cause microstuttering almost all the time when you switch to it).

*Edit*

NONE of the VT's work properly for 165hz. They all do 2 second interval frameskipping with a few doing massive frameskipping (VT 1097). Can't go higher than 165hz because of 6 bit color depth makes overwatch look ugly, from my testing of 125hz with VT 1500 (6 bpc). I tested 1089 to 1101. Tried a couple of 160hz also and still the 2 second frameskipping.

[Chief Blur Buster]

Going to test other Vertical Totals close to this value to see if it goes away (example, this has to be done at stuff like 85hz refreh rate with a VT tweak--VT 1501 works fine but other VT's in the 1497-1502 range will cause microstuttering almost all the time when you switch to it).

Pressing the S-Switch about 3 to 4 times sometimes kills the microstuttering.

Can't go higher than 165hz because of 6 bit color depth makes overwatch look ugly, from my testing of 125hz with VT 1500 (6 bpc).

But above-165Hz works for you, right?

I get full 8bit color depth at 220Hz. 6-bit FRC is still working properly on my unit at 220Hz, properly generating 8-bit color depth.

The color clip issue is not a 6-bit issue.

I don't need to use ToastyX, the 4:2:2 tricks, and the HDTV color range limiting (unless I am going beyond, like 240Hz).

So your limits are as follows:
220Hz -- works with NVIDIA Control Panel, full 4:4:4, full 8bit via usual 6bit+FRC, just needs color recalibration
250Hz -- requires ToastyX CRU, 4:2:2, and colors will be worse

If you care about 8bit and full color quality, you should not go above ~220Hz.

At 220Hz via S-Switch, the only problem is that my gamma/brightness/contrast is way out of whack (clipping saturated colors), but I can fix that using Entech Taiwan SoftMCCS (to avoid touching monitor menus that makes "Out Of Range" reappear). That brings top end of the full 8bit color range back into play. XL2720Z weren't really well-calibrated out of the box, if you're very picky about colors and the S-Switch buttons switches to a color-range-clipped mode.

You can also use NVIDIA Control Panel color adjustments instead of SoftMCCS, but you will have some color-roundoff effects from 8-bit remapping to 8-bit, so best to adjust via SoftMCCS to preserve more colordepth. Remember to record your calibration because pressing S-Switch will cause it to forget the color calibration.