PowerBook G4 and Mac mini G4 meet Ultra HD (sort of) and WQUXGA

[Amethyst1]

So I recently picked up an Atlona DP-400 Dual Link DVI to Mini DisplayPort converter very cheaply, and used it to connect my 15in PowerBook5,6 (early 2005 1.67 GHz with dual-link DVI) to my Dell P2415Q monitor.

The good news is that 3840×2160 at 30 Hz works and is displayed properly at first glance. Panther, Tiger and Leopard are really majestic at that resolution, even though the monitor's size (23.8 inches) makes everything very small (I'll say I like it that way, however ).

However, there's framebuffer corruption (i.e. it also shows up on screenshots, not just the monitor itself) going on starting at a width of about 2660 pixels. Windows seemingly disappear when they're dragged across that boundary, and dragging them back reveals that the wallpaper is showing in the parts that were across the boundary. The desktop itself including the menu bar and icons and full-screen applications are not affected, though.

This screenshot illustrates the problem - the right part of the Safari window simply disappears:

2560×1440 at 60 Hz works perfectly. I'll have to see (1) if I get a similar behaviour when running Linux on the PowerBook and (2) if this problem disappears on Mac OS X when using a resolution that's not wide enough to run into this boundary; e.g. 2624×2160 or something like that - UPDATE: no problems at 2656×2160.

I'm fully aware of the fact that the PowerBook's GPU never "supported" resolutions higher than 2560×1600 but it's fun to see how far one can make the old machines go...

 

[LightBulbFun]

this is pretty Awesome!

its something I have theorised would be possible for a while since Dual link DVI has enough bandwidth for 4K at 30Hz (its the same as HDMI 1.4). but I dont own a 4K monitor to test it. (I do own a 1440p one and i was able to get 2560x1440 at 30Hz out of a Single link DVI port which was fun )

so its pretty cool to see someone else test it does your monitor have a HDMI input? if so can you do 4K 30Hz via a DVI to HDMI cable? (ie removing the DVI to DP adapter from the loop)

interesting on the corruption does it happen in Leopard as well?

also do you own a DLSD? there GPUs have a newer ROM revision (-169 IIRC) I wonder if they have the same issue.

 

[Amethyst1]

I've also been thinking about that - the pixel clock for 2560×1600 at 60 Hz is ~270 MHz; for 3840×2160 at 30 Hz it's ~262 MHz. Theoretically, fully exploiting DL-DVI's 330 MHz pixel clock limit should allow a 37 Hz refresh rate. I'll have to look into that.

The monitor has HDMI but since I only have a "crappy" DVI-to-HDMI cable which is single-link, 1920×1080 at 60 Hz is the highest setting which will work out of the box when driven by the PowerBook using this cable. The system actually allows me to select the higher resolutions but since Mac OS X switches to a dual-link signal the monitor only shows a garbled image. What's slightly interesting is that 2048×1152 at 60 Hz is also output as a dual-link signal despite its pixel clock being lower than the single-link limit, which explains why it only works when using the Atlona converter and not when using the single-link connection.

The corruption is the same in Panther, Tiger and Leopard. I have noticed that once the mouse cursor has crossed the "invisible boundary", I can't bring up the right-click menu or click on desktop icons either.

I only own a SLSD, unfortunately but hope to be able to add a DLSD to my collection

 

[Amethyst1]

I apologise for bringing up that thread again but I recently experimented some more with the DP400/P2415Q combo.

So, on the 15in PB with the 128MB 9700 and dual-link DVI running at 3840×2160, framebuffer corruption appears at a width/horizontal res of 2656 pixels, which led me to try a custom mode of 2656×2160 which works perfectly. Right now I'm running this at 43 Hz refresh, for no other reason that the required pixel clock is about 270 MHz, which is known to work for 2560×1600 at 60 Hz. 2656×2160 at 50 Hz (311 MHz pixel clock) results in drop-outs but I'm not sure if the GPU or the converter is the culprit; I'll keep testing.

I also tried a 12in 1.5GHz PB with the 64MB Go5200 but can only get 1920×1080 at 60 Hz to work, and even that has occasional drop-outs (but 1920×1200 at 60 Hz on a 23in acrylic ACD works fine – go figure...). Modes that are soundly within the 165 MHz pixel-clock limit for single-link DVI – I'm aiming even lower and don't exceed 154 MHz – all resulted in a black screen but with the screen's menu curiously correctly reporting the mode I defined.

My totally uneducated guess is that OS X, at least on the machines I use, tries to output a dual-link signal if the (horizontal?) resolution exceeds a certain limit (maybe 1920 pixels?), even if the hardware isn't technically capable of doing that. The fact that 2048×1152 at 60 Hz doesn't display via single-link but does via dual-link (both tested on the 15in) even though the pixel clock is just 156 MHz might support that hypothesis.

The question is, then: How to make OS X output single-link signals regardless of the horizontal resolution so I can hook up the beast to the little 12in?

 

[LightBulbFun]

I apologise for bringing up that thread again but I recently experimented some more with the DP400/P2415Q combo.

So, on the 15in PB with the 128MB 9700 and dual-link DVI running at 3840×2160, framebuffer corruption appears at a width/horizontal res of 2656 pixels, which led me to try a custom mode of 2656×2160 which works perfectly. Right now I'm running this at 43 Hz refresh, for no other reason that the required pixel clock is about 270 MHz, which is known to work for 2560×1600 at 60 Hz. 2656×2160 at 50 Hz (311 MHz pixel clock) results in drop-outs but I'm not sure if the GPU or the converter is the culprit; I'll keep testing.

I also tried a 12in 1.5GHz PB with the 64MB Go5200 but can only get 1920×1080 at 60 Hz to work, and even that has occasional drop-outs (but 1920×1200 at 60 Hz on a 23in acrylic ACD works fine – go figure...). Modes that are soundly within the 165 MHz pixel-clock limit for single-link DVI – I'm aiming even lower and don't exceed 154 MHz – all resulted in a black screen but with the screen's menu curiously correctly reporting the mode I defined.

My totally uneducated guess is that OS X, at least on the machines I use, tries to output a dual-link signal if the (horizontal?) resolution exceeds a certain limit (maybe 1920 pixels?), even if the hardware isn't technically capable of doing that. The fact that 2048×1152 at 60 Hz doesn't display via single-link but does via dual-link (both tested on the 15in) even though the pixel clock is just 156 MHz might support that hypothesis.

The question is, then: How to make OS X output single-link signals regardless of the horizontal resolution so I can hook up the beast to the little 12in?

the 12 inch PB issue is probably the weak TMDS transmitter of the GeForce FX 5200. (the G5 cards use external transmitters to get round the issue I dont know if the PBs do or dont)

1920x1080 or specifically 1080p is more demanding then classic 1920x1200, I cant recall the specifics of why but I do know from poking around in switch rez that i noticed the clock is higher for 1080p

I managed to do 2560x1440@30Hz from a Radeon 9200 in 10.5.8 which was quite fun

(and iv frequently shown off System 7 running at 2048x1152@60Hz from said card too )

 

[Amethyst1]

the 12 inch PB issue is probably the weak TMDS transmitter of the GeForce FX 5200. (the G5 cards use external transmitters to get round the issue I dont know if the PBs do or dont)

I'd thought of that which is why I kept the PCLK under 154 MHz in my experiments. However, I don't know if the 12in actually has tweak TMDS transmitters.

1920x1080 or specifically 1080p is more demanding then classic 1920x1200, I cant recall the specifics of why but I do know from poking around in switch rez that i noticed the clock is higher for 1080p

I wasn't aware of that; many thanks for clearifying this. Another reason to hate "1080p" and other uselessly low 16:9 resolutions.

Next step is to try my 1.33GHz mini with the combo

 

[Amethyst1]

Small update: Thought I'd try the screen with a 1.33GHz 12in PowerBook running Jaguar, since it predates the dual-link DVI matter. A great idea indeed...

Using the active DVI-to-DP adapter, the screen is recognised and several resolutions up to 3840×2160 are offered. None of them work and the screen remains a solid black. I also get occasional corruption on the internal LCD. Using a straight DVI-to-HDMI connection causes both the "4K" monitor and the PowerBook's LCD to get corrupted beyond recognition and that's that.

 

[Amethyst1]

It's not a PowerBook, but... I can coax 1280×720 in HiDPI out of a 2006 MBP running Lion on this monitor. I wonder if Mountain Lion allows going higher. Actual resolution is 3840×2160@30Hz.

 

[LightBulbFun]

very cool stuff

I need to get myself one of those Atlona DP-400 Dual Link DVI to Mini DisplayPort adapters at some point

it would be fun to finally see my main dell monitor being driven at 2560x1440 60Hz from one of my many PowerPC macs

(it has 2 HDMI 1.4 ports but the monitor does not like a dual link DVI signal sadly)

 

[Amethyst1]

Small update: MBP is now running 10.8.3 via MacPostFactor; still won't go higher than 1280×720 in HiDPI. Time to fire up Software Update.

 

[LightBulbFun]

small update for this thread

@Amethyst1 has kindly donated his Atlona DP-400 to me to play with (he also donated a couple cool motherboards for me to play with )

iv only just got it in today so have not yet had much time yet to play around with it, but couldn't resist trying it out my 15 inch DLSD

where im pleased to report it works perfectly with my Modern Dell U2715H monitor at full 2560x1440@60Hz with no issues

its pretty cool to see Tiger at full resolution with full acceleration on this monitor as before I had not been able to do so

it will be interesting to see what the whole setup does with a single link DVI output etc

(I wonder if with some poking and prodding I can use this setup to do 2560x1440 in OS 9 )

 

[Amethyst1]

Another small update since I acquired an IBM "Bertha"...

- 12in 1.33GHz PowerBook with 32MB GeForce FX5200: unusable due to heavy corruption on both internal and external screen. Corruption appears as soon as the grey Apple logo. Tested with Jaguar and Tiger.

- 12in 1.5GHz PowerBook with 64MB GeForce FX5200: unusable due to heavy corruption on both internal and external screen. Corruption appears as soon as the grey Apple logo. Tested with Tiger.

- 15in 1.67GHz PowerBook SLSD with 64MB Radeon 9700 and single-link DVI: 3840×2400 at 13 Hz works at 32,768 colours but framebuffer corruption appears like it does with the Dell display. Tested on Tiger and Leopard.

- 15in 1.67GHz PowerBook SLSD with 128MB Radeon 9700 and dual-link DVI: 3840×2400 at 13 Hz works at "millions" of colours but framebuffer corruption appears like it does with the Dell display. Tested on Tiger and Leopard.

- 1.33GHz Mac mini with 32MB Radeon 9200: 3840×2400 at 13 Hz works at 32,768 colours. No framebuffer corruption. Boots at 1920×2400 but OS X Tiger and Leopard switch to full resolution when WindowServer loads. Jaguar displays a broken greyscale 1920×2400. OS 9.2.2 only displays up to 1920×2400 as well, trying to switch to full resolution results in heavy corruption. Several lower resolutions work but others don't.

- 15in 500MHz PowerBook Ti with 32MB VTBook: 1600×1200 at 60 Hz is highest resolution offered in OS 9.2.2.

- 15in 800MHz PowerBook Ti with 32MB Radeon 7500: 3840×2400 at 13 Hz works at 32,768 colours if in clamshell mode - if the internal LCD is also active, only 256 colours are possible. No framebuffer corruption. Tested on OS 9.2.2, Puma and Jaguar.

 

[Amethyst1]

Changed thread title since it's about 3840×2160 and 3840×2400 now.
Added more data points to previous post.

 

[Amethyst1]

New toy

This is a clone of the Atlona DP-400. I'm planning to do some systematic testing with regards to its pixel clock limits.

 

[Amethyst1]

Some ramblings...

Since the GMA X3100 in my MacBook4,1 doesn't even acknowledge that Bertha is there, I tried something crazy - connect the Atlona box to go from DVI to DP and then daisy-chain an active DP to DVI converter to go back to DVI. Unsurprisingly, that didn't work either, but it's possible that the Atlona's DP output doesn't provide enough (any?) juice for the converter (and my converter doesn't allow providing external power).

However, I also discovered that if the Atlona is hooked up to the system without any monitor connected to it, a phantom LED Cinema Display shows up, with the resolutions offered being 640×480, 800×600, 1024×576 and 1280×720 - so it does have some "fallback" EDID of its own that is normally overriden by the monitor's EDID.

 

[Amethyst1]

Update: got Jaguar running on a 17" PowerBook G4 (PowerBook5,5) with a 64 MB Radeon 9700... and am getting the same ol' framebuffer corruption at 3840×2400.

 

[timidpimpin]

30hz must be rough for video or even faster scrolling.

 

[Amethyst1]

30hz must be rough for video or even faster scrolling.

Scrolling is brutal (video recorded at 24/25 fps isn't too much of a problem) but dual-link DVI is only specced for a 330 MHz pixel clock (some GPUs can go higher) which gives you 37 Hz at 4K.

 

[Amethyst1]

However, I also discovered that if the Atlona is hooked up to the system without any monitor connected to it, a phantom LED Cinema Display shows up, with the resolutions offered being 640×480, 800×600, 1024×576 and 1280×720 - so it does have some "fallback" EDID of its own that is normally overriden by the monitor's EDID.

Update on that - @r6mile and I just discovered the Atlona stores the name and settings of the monitor connected to it; if it's hooked up headlessly afterwards, it acts as if the monitor were still there, so it might not have a fallback EDID of its own after all.

 

[LightBulbFun]

Update on that - @r6mile and I just discovered the Atlona stores the name and settings of the monitor connected to it; if it's hooked up headlessly afterwards, it acts as if the monitor were still there, so it might not have a fallback EDID of its own after all.

ah yeah, when I got your old one, it still had your Dell's 4K monitor stored in it

that was fun to play with for a bit until I cleared it and hooked up my own monitor into it

 

[Amethyst1]

that was fun to play with for a bit until I cleared it and hooked up my own monitor into it

4K is fun, eh?