Overclocking Desktop LCDs past 144Hz questions

[Comanglia]

I've done a lot of dabbling with this, and the highest stable refresh rate I've ever got on a Desktop LCD was 151Hz (the highest I got to display at all was 154Hz). I achieved this on a BenQ XL2420TE using heavily reduced LCD timing setting, at 1600 x 900. Though according to the math I did the cable I was using (Display Port 1.2)

This is what the frequencies would look like

The Max I've got
Pixel Clock 230.74 MHz
Horizontal 137.263kHz
Refresh 151Hz
1600 x 900

Typical 144Hz 1080p monitor
Pixel Clock 317.49MHz
Horizontal 158.112kHz
Refresh 144Hz
1920 x 1080

Now the highest setting for 1600 x 900 that hits any of the "caps" from the typical 144Hz at 1080p
Pixel Clock 260.58MHz (well below that of the 1080p setting)
Horizontal 157.260kHz (slightly below that of the 1080p setting)
Refresh 173Hz (quite a bit higher)
1600 x 900

before anyone says that it's related to bandwidth it isn't and here's a very brief why.
1920 x 1080 = 2,073,600
1600 x 900 = 1,440,000
2,073,600 / 1,440,000 = 1.44 (meaning 1080p has 44% more pixels and 44% more bandwidth to use at the same refresh rate)
144Hz x 1.44 = 207.36 (so the equivalent bandwidth of 1080p 144Hz for 900p would be 207Hz)

so if the lowest refresh rate for 1600 x 900 that would match the frequencies (or be below them), while using less bandwidth is 173Hz. Then WHY is the highest stable refresh rate 151Hz?

Guesses
Firmware ???
Hardware/backlighting ???

[Falkentyne]

Can you list the EXACT CRU Timings you used on your XL2420TE?
I was unable to replicate them on my XL2720Z, and I was only able to get the horizontal kHz and pixel clock to match up with 151 hz by changing around the porch and sync numbers after entering the pixel clock manually. Went out of range like a boss.

Can you post the front porch pixels/lines, sync width pixels/lines, back porch p/l, blanking (if necessary, I think blanking fills in automatically) and the total Horizontal total and Vertical total (e.g. 1681, 909) you used ?


I think,
Everything gets thrown off once you go past the limit of standard timings. Then it's just completely YMMV.
You should be able to go up to 129 hz with standard timings. But 1 more hz= out of range. And it's not the cable causing it.

Once you reduce the timings to LCD reduced, you can go up to 145 hz. Then 146 hz: out of range. Everything else like getting to 151 hz on whacky timings has to do with what the scaler will accept. You know you can display a 1920x1440@100 hz image on that 2420TE also, right? But you will get an out of range error although you will still see an image (the OOR error is the scaler not liking the timings but still able to display the image; this error can be closed by choosing the same input signal, but you can't enter the OSD; black screen out of range errors are hard limits and can not be closed). You can get rid of the OOR error by increasing the vertical total a bit (up to 1502).

[Comanglia]

Can you list the EXACT CRU Timings you used on your XL2420TE?
I was unable to replicate them on my XL2720Z, and I was only able to get the horizontal kHz and pixel clock to match up with 151 hz by changing around the porch and sync numbers after entering the pixel clock manually. Went out of range like a boss.

Can you post the front porch pixels/lines, sync width pixels/lines, back porch p/l, blanking (if necessary, I think blanking fills in automatically) and the total Horizontal total and Vertical total (e.g. 1681, 909) you used ?


I think,
Everything gets thrown off once you go past the limit of standard timings. Then it's just completely YMMV.
You should be able to go up to 129 hz with standard timings. But 1 more hz= out of range. And it's not the cable causing it.

Once you reduce the timings to LCD reduced, you can go up to 145 hz. Then 146 hz: out of range. Everything else like getting to 151 hz on whacky timings has to do with what the scaler will accept. You know you can display a 1920x1440@100 hz image on that 2420TE also, right? But you will get an out of range error although you will still see an image (the OOR error is the scaler not liking the timings but still able to display the image; this error can be closed by choosing the same input signal, but you can't enter the OSD; black screen out of range errors are hard limits and can not be closed). You can get rid of the OOR error by increasing the vertical total a bit (up to 1502).

I'm going tbh I don't remember -exactly- what settings I had, it's been awhile. I just got reminded of it today, and just did some quick estimates of the figures I used.

Though you have me wondering if their's certain manual timings that will work and be stable over 151Hz now though.

[Q83Ia7ta]

Locked by firmware. May be this hardware also can't push more even with hacked firmware.

http://www.blurbusters.com/true-240hz-l ... s-project/
http://forums.blurbusters.com/viewtopic.php?f=7&t=48

Author made it with modified pcb of korean 2560x1440p ips monitor that can be overclocked to 120Hz.

imho vendors don't go higher than 144Hz because there is some picture quality (color) degradation due panel physical specs and so few people who need more than 144Hz.

[Falkentyne]

DEFINITELY locked by firmware.
Asus VG248QE and Benq XL2411Z /2420Z/2430T are the exact same AU Optronics panel.

VG248QE can do 150hz at 1280x720 and 1600x900 (dfferent timings for each). The Benq monitors can't (those timings ToastyX posted for the VG248 don't work on the Benq, even though it's the EXACT Same physical panel. The firmware won't allow it).

[Comanglia]

Locked by firmware. May be this hardware also can't push more even with hacked firmware.

http://www.blurbusters.com/true-240hz-l ... s-project/
http://forums.blurbusters.com/viewtopic.php?f=7&t=48

Author made it with modified pcb of korean 2560x1440p ips monitor that can be overclocked to 120Hz.

imho vendors don't go higher than 144Hz because there is some picture quality (color) degradation due panel physical specs and so few people who need more than 144Hz.

Holy shit!

I definitely need to learn how to do that, then again I don't have a bunch of extra money to blow on possibly ruining my monitor lol.

[Profiled]

Some intresting monitro from korea. 200Hz OC from one user in reddit. Qnix QX2414 korean only DVI model.

OCN(http://www.overclock.net/t/1559401/qnix ... t_24387805)