So, after trialling the BenQ PD3225U 4K monitor with my new Mac Studio M4 Max, I am comparing it with the PD3226G 4K. I have 2 immediate questions:
1) the monitor is 144Hz, so why can I only set it to 100Hz in Settings>Display?
2) HDR is not available unless I lower the frequency from 100Hz to 60Hz. Is this correct?
Thanks in advance.
[Re-Titled by Moderator]
Mac Studio, macOS 15.3
4k 8 bits color 120 Hz
(just under) 4K, 10 bits color 100 Hz
that does not seem puzzling to me.
the table for 10 bits color are the next-to-last HUGE green and pink large tables near the end of the Wikipedia article
the 8 bits table are up a page or so.
https://en.wikipedia.org/wiki/DisplayPort
So, I think from your reply, this is where we have the confusion. I am getting nominal 4K (3840x2160) and HDR at 144Hz, and I am not getting it at lower resolutions like 3360x1890, where it is restricted to 100Hz and no HDR. This is the reason for my question from the start.
Please see attached.
that BenQ PD3225U display appears to be a 4K display with HDR
Connectivity:
HDMI (v2.0). <-- this is unfortunate, because it severely limits the highest resolutions to
50 Hz refresh rates without compromising number of colors.
HDMI 2.1 would be FAR better, allowing up to 144 Hz. but the display does not support that
2
DisplayPort (v1.4)
1
Thunderbolt 3 ( PowerDelivery 85W, DisplayPort Alt Mode, Data )
a USB-C connection allow the use of 4K at 60 Hz. if you drop to 8 bits/color, you can attain 75 Hz.
For higher refresh rates, you MUST connect this display with a genuine ThunderBolt cable, marked with the Thunderbolt trademark, or you will never see high refresh rates at HDR 10 bits/color.
ThunderBolt cables for this use should generally be 0.5 meters or shorter, unless you are using (expensive [over US$100]) tuned ACTIVE ThunderBolt cables.
-------
you also have the option to connect with TWO data cables, and send the left or right half-display over each cable. It sounds much more complex than it actually is, and readers report it works great.
So, looking into this a bit more, it's even more confusing. The options available are dependent on the resolution.
1920x1080 - 144Hz and HDR
2560x1440 - 144Hz and HDR
3008x1692 - 120Hz and no HDR
3360x1890 - 100Hz and no HDR
3560x2160 - 144Hz and HDR.
When I wrote the first post, I was running at 3360x1890.
Can anyone explain this?
Don't know what's going on in this thread as my later post appears before the previous one!
Oh well..
The TB cable is 1.0m, but did you see my post above regarding resolutions?
The max res, i.e. 2160p, gives the full choice, i.e. up to 144Hz and HDR.
<< 1) the monitor is 144Hz, so why can I only set it to 100Hz in Settings>Display? >>
Because there is not enough bandwidth in a typical Thunderbolt cable to run any faster than what you are achieving.
<< 2) HDR is not available unless I lower the frequency from 100Hz to 60Hz. Is this correct? >>
Yes, because there is not enough bandwidth in a typical ThunderBolt cable to do that.
If you want the data rates you are asking about, the Thunderbolt cable has to 'gear-shift' from its current HBR3, about 26 G bits/secs up to the next step, UHBR10, which runs just shy of maximum outbound speed of 40 G bits/sec.
This is ONLY possible with Thunderbolt cables shorter than 0.5 meters, or with tuned ACTIVE cables that cost a lot more.
I don't know what's going on with the order of posts here, but maybe you missed my earlier post showing that all the options are available to me.
Here is what I said, in case you missed it:
'So, looking into this a bit more, it's even more confusing. The options available are dependent on the resolution.
1920x1080 - 144Hz and HDR
2560x1440 - 144Hz and HDR
3008x1692 - 120Hz and no HDR
3360x1890 - 100Hz and no HDR
3560x2160 - 144Hz and HDR.
When I wrote the first post, I was running at 3360x1890'.
What I don't get is why the highest res - native 2160p - has all options available - 144Hz and HDR - when some lower resolutions don't.
I am having no problem reading your posts -- I have my Forums settings for chronological order -- perhaps yours is set to something different?
I read the resolutions you posted. Each and every once conforms with what is expected with the setup you have.
Resolution, refresh rate, and number of bits/color all conspire to drive up the overall data rate required. With the computer, the cables, and the display you have, you have now successfully enumerated what is possible.
I have also stated what it would take to get the rates you desire.
Sorry, I don't understand.
Why would the highest res, i.e. 3560x2160, allow the most options - 144Hz and HDR? I would logically think that the highest res would be making the most demands on data bandwidth.
It is not just s simple bit/sec calculation. There are 'brackets' similar to tax brackets, that are supported. But if you calculated precisely, rather than intuitively, I expect the results would be the same.
3560x2160 at HDR yields a refresh rate just shy of the absolute maximum data rate that is possible. Others miss by a wide margin, but the next combination step up in any dimension may push you beyond the limit.
There are some limits tables on wikipedia I could point you to, and you could look up the major settings yourself if you like.
you should be able to get 120 Hz at full 4K with 8 bits/color, but there may not be a settings for that.
your 3560x2160 'gets by' at just shy of 4K. The tables shows full 4K with HDR can attain 98 Hz. Since you dropped a few rows and columns, you get 100, but it is AT the limit.
I'm still struggling with this, sorry.
I just cannot see why lower resolutions are more restricted in refresh rates and HDR in Settings>Display. Makes no sense to me despite your best attempts to explain.
In games, I can get 144fps in 4K, but only 100fps in resolution below that, i.e. 3360x1890 (and no HDR). Completely counter-intuitive to me.
What tables are you referring to?
HBR2 is the speed you can can get on a USB connection when the cables are under a meter. The basic rate is 10 G bits/sec, and then it 'turns around' and runs the inbound lanes as outbound lanes part of the time, to get a speed of 17.28 (less than the nominal 20 max).
HBR3 requires a Thunderbolt cable, which effectively runs twice as fast as USB. When you try to run a one meter ThunderBolt cable as high as UHBR10 data rate, it makes too many errors and falls back to the slower HBR3 speed. You need a 0.5 meter Thunderbolt cable, or an ACTIVE cable to get the top data rate.
‘4k 8 bits color 120 Hz
4K, 10 bits color 100 Hz’
But the point is, I am getting 144Hz in 4K HDR10!
I’m confused by the table. Surely that’s for DP. I’m running on Thunderbolt 5 from Mac to Thunderbolt 4 on monitor.
you are NOT running 4K, you dropped your row width much lower. 3840-3560 is 280 columns of data, times 2160 * [10 bit Bytes] each! That's 6,048,000 bits PER FRAME * whatever refers rate -- not trivial -- and maybe that's what lets you get in under the wire.
when you are running "ThunderBolt" the protocol you are actually running is DisplayPort-over-Thunderbolt.
ThunderBolt 5 only adds speed when the Port, the cable, and the external device ALL support Thunderbolt-5. Otherwise, it is running at ThunderBolt 3-4 speeds.
Mac Studio M4 Max and BenQ PD3226G Display: HDR and Refresh Rate Limitations
