30 Cinema Display constricted resolution

[Agincourt]

I bought an old 30 Cinema Display and linked it with an old Powerbook G4 (15 in) + newer iMac with an adaptor. Same problem, the resolution maxes out at 1200 x 800. I've looked around and supposedly I needed to update the powerbook to include a display profile or something, but it's already maxed out at 10.4.11 Meanwhile there's no reason the iMac (2012) can't use its native resolution of 2050 x 1600. I'm unsure whether it's worth my effort buying a USB C adapter if the resolution is this terrible.

Anyone else have this problem? Solutions?

 

[joevt]

2560x1600 60Hz requires Dual Link DVI.

Exactly which PowerBook G4?
https://everymac.com/systems/apple/powerbook_g4/index-powerbook-g4.html

Apple PowerBook G4 1.0 15" (FW800 - Al) only supports up to 2048x1536 although I'm not sure if that's true.
Apple PowerBook G4 1.67 15" (DLSD/HR - Al) can support 2560x1600.

Which adapters did you use on the iMac? You need an adapter that supports Dual Link DVI. It needs to be an active adapter. Some adapters might be passive, which means they get a DVI single link (or HDMI) signal from the DisplayPort port using the DisplayPort Dual Mode feature (DP++).

USB-C ports (Thunderbolt or USB4) ports don't support DP++. They use DisplayPort Alt Mode to output DisplayPort but cannot use DP++ to output DVI single link or HDMI. USB-C to DVI single link (or HDMI) or Dual Link DVI adapters are always active adapters.

Note that DisplayPort to Dual Link DVI adapters cannot work from most USB-C dock that supports USB 3.x since those only have 2 lanes of DisplayPort and the adapter requires 4 lanes. However, if the USB-C dock has a MST hub (such as the CalDigit SOHO) then the MST hub can convert 2 lanes of HBR2 or HBR3 to the 4 lanes of HBR that the adapter requires. An external MST hub connected to a USB-C dock can also do the conversion.

If you have all the correct adapters, then you may need to install SwitchResX to see if it shows a 2560x1600 mode. If not, then use SwitchResX to create a custom timing for the 2560x1600 mode. The details are in the EDID of the display which SwitchResX can extract for you.

 

[Amethyst1]

Apple PowerBook G4 1.67 15" (DLSD/HR - Al) can support 2560x1600.

All DLSD/HR PowerBooks (15" and 17") have dual-link DVI. Additionally, the high-end configuration (128 MB VRAM) of the early 2005 non-DLSD/HR PowerBooks also has dual-link DVI.

Apple PowerBook G4 1.0 15" (FW800 - Al) only supports up to 2048x1536 although I'm not sure if that's true.

Nope.

 

[Agincourt]

I do have a 1.5ghz G4 powerbook, although I can get my hands on one that's 1.67... both limited to 64 MB graphics. Still I'm at a loss as to why the resolution max is so low. Also can't figure why Apple didn't equip the G4 Mini or the 12 powerbook to operate this display.

I think I do have a passive adaptor for the iMac. I've ordered a duel link adaptor and expect it in a few days. Still it's odd to see a larger display with less than half the resolution of my non-retina iMac. It's so pixelated I can barely tolerate using it as a second screen. It's good enough watching a DVD though.

On an unrelated note, the design of the 30 display is terrible. The cables linking to the brick are extremely short and I can't easily tuck them behind the desk/table. The data cables should have had their own 'branch' separate from the brick. Now that I need a dongle for the USB-C, it's a mess of cables.

 

[Amethyst1]

I do have a 1.5ghz G4 powerbook, although I can get my hands on one that's 1.67... both limited to 64 MB graphics.

You absolutely need a 2005 15”/17” PowerBook G4 with 128 MB VRAM. Only these have dual-link DVI.

Still I'm at a loss as to why the resolution max is so low. Also can't figure why Apple didn't equip the G4 Mini or the 12 powerbook to operate this display.

The reason for the low resolution is that you only have a single-link DVI connection (one TMDS link). The 30” Cinema HD Display will only do 1280×800 in this case. For 2560×1600, you absolutely need dual-link DVI (two TMDS links), which neither the 12” PowerBook G4 nor the Mac mini G4 have. There’s nothing in between in terms of resolution on the Cinema HD Display. It’s either 1280×800 or 2560×1600. (All early 30” LCDs are like that.)

 

[mcnallym]

I have the Dell 3008WFP which drive through Displayport but yes the DVI on it unless had a good dual-link DVI cable topped out at a lower resolution.

 

[Amethyst1]

I have the Dell 3008WFP which drive through Displayport but yes the DVI on it unless had a good dual-link DVI cable topped out at a lower resolution.

The Dell 3008WFP will do 1920×1200 via single-link DVI though. The Apple Cinema HD Display won't.

 

[Agincourt]

I have just bought a dual link DVI and the resolution is STILL only 1280 x 800. That's literally all this display will ever do! A MacBook Pro and a 2017 mini both can't make it work.

Does anyone know any problems that limit the resolution not attributed to what's been presented?

 

[Amethyst1]

I have just bought a dual link DVI and the resolution is STILL only 1280 x 800.

Post a link to the adapter you bought.

Does anyone know any problems that limit the resolution not attributed to what's been presented?

In System Preferences > Displays, click on “Scaled” while holding Alt/Option. Is the native resolution listed?

 

[Agincourt]

Actually my adaptor probably isn't dual link. Generic device... getting frustrated that not one of the multiple devices I own can use it properly! New one coming in as late of 5/30

 

[Agincourt]

Now I've got the right adaptor and the thing still isn't working.

I get the 'standard' low resolution at startup and log in, then it goes black and doesn't reconfigure. Is this a software problem? I think that I recall hearing the Cinema Display (outdated) requires software to make it work.

 

[Amethyst1]

Now I've got the right adaptor and the thing still isn't working.

Can you post a link to the adapter?

I get the 'standard' low resolution at startup and log in, then it goes black and doesn't reconfigure.

Use "Gather Windows" after opening System Preferences > Displays and try setting the resolution of the ACD to 2560×1600. If that doesn't work, an AllRez dump (saved as a text file and attached to this post) would be helpful to see what's going on.

I think that I recall hearing the Cinema Display (outdated) requires software to make it work.

Nope. Just a dual-link DVI connection.

 

[Agincourt]

EDIT:

I finally got an adaptor suitable for the display. I had some trouble configuring it but got the desired resolution while using my 2019 MacBook Pro. However I've plugged it into my Mac mini and it's still not working, although this may be attributed to using the older 10.14 operating system. Why is it not allowing me to view all the potential resolution options?!

 

[joevt]

If that doesn't work, an AllRez dump (saved as a text file and attached to this post) would be helpful to see what's going on.