27" iMac 2017 with LG 24ud58 external monitor Low Resolution

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Level 1

5 points

27" iMac 2017 with LG 24ud58 external monitor Low Resolution

Hi,

I have an iMac 2017 27" and wanted a high resolution external monitor (albeit budget) so opted for the LG 24UD58-B - Monitor has x2 HDMI and x1 Display Ports

I also use this with a HP Docking station for my works Laptop and it happily displays in 3840x2160 and 2560x1440 with many other lower options and is very crisp right up to 3840x2160.

On the iMac is where I have issues ... Looking at the scaled resolutions the default is 1920x1080 and this is ultra crisp.

Scaled options for 3840x2160 is shown as "(low resolution)" and whilst the iMac will support this the monitor is obviously not clear - Ideally I want to run 2560x1440 which I can get too via holding alt/option and clicking on the Scaled option in Displays (Settings) but once again shows as "(Low Resolution)"

I am using an iMac so USB-C ports to a Lenovo USB-C hub to a HDMI 2.0b 4K @ 60hz/2160p cable to the Monitor. The hub suggests supporting 4K HDMI.

So my challenge is to get a non Low Resolution 2560x1440 like I do on my works HP as this size / scale / resolution is what sits nice against the iMac for the work I want to use it for.

Any ideas or have I got a pup!!!

iMac 27" 5K, macOS 10.14

Posted on Apr 15, 2019 9:05 AM

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Answer 1

Johnb-one

Level 6

9,180 points

Apr 15, 2019 7:04 PM in response to uktricky13

I'd say go for DisplayPort. The only 2 Lenovo USB-C things I could find, are a ThinkPad USB-C Dock which has 2 displayPorts, and a bunch of other stuff and costs around $300. There is also the USB-C Travel hub for around $ 120, which has 1 vga, 1 hdmi, 1 usg and 1 Network/Ethernet connector. apparently you can only connect 1 monitor to that hub at one time. Oh....and check the cables. Dunno why exactly, but High Resolution whatever requires special HDMI 2.0 cables and DisplayPort 1.4, I think. just check to make sure it says supports 4k when you get 'em. Uktricky 13 ? Yes, I can believe it. You've kinda got me boxed into a corner now. You also have to make sure it supports your model of iMac (the 2017 one) which is not guaranteed. If it's not there in writing, then probably not. This link is all I could come up with from Lenovo. They don't mention Mac at all, imac or macbook Pro. Instead we get some kinda Excel files. I'll leave this to you to sort through. There's a bacon buttie that's calling my name at the moment

https://support.lenovo.com/ca/en/solutions/accs-guide

apparently though, your iMac will do DisplayPort over USB-C or Thunderbolt 3. If you want HDMI, you're going to have to use an adapter

John B

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Answer 2

Johnb-one

Level 6

9,180 points

Apr 16, 2019 5:57 PM in response to Malcolm J. Rayfield

Yes... you may be correct. It says compatible with macbook pro 2017 and it does output 4k from hdmi but doesn’t say what frequency( 60 hz or 30 hz) . I’d also suggest seeing if there’s a firmware update for the LG monitor in question. On my LG monitor, you have to download and install ‘ on screen control’ and of course the usb-c cable has to be connected for that, even if you don’t have a usb-c socket on your mac. lg has provided a usb-c to usb-a adapter. Mst ( multi stream threading has to be on and displayport 1.4. But you’re using hdmi... any particular reason for that? Lg sez you can use usb-c for video or displayport. Unfortunately the longest usb-c cable i’ve found around here is about 6 feet. I suppose clicking on ‘detect displays ‘ under system prefs does nowt ( nothing)

well, i’m out of ideas. Could be a bad hub?

Jb

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Answer 3

uktricky13 Author

Level 1

5 points

Apr 20, 2019 1:08 AM in response to uktricky13

Given I really only wanted 2560x1440 - I picked up a Lenovo L24Q-10 and I have to say for the price £149 @ Currys (UK) it rocks

Single HDMI and DisplayPort and both work quite happily at that resolution from my iMac

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Answer 4

uktricky13 Author

Level 1

5 points

Apr 16, 2019 1:05 PM in response to uktricky13

Appears it is down to my monitor

Tried an old ACER G247HYU and this works perfectly at 2560x1440 (The max resolution of this screen) using both the USB-C to DisplayPort and the Lenovo Hub via HDMI with refresh rate reported at 60Hertz

So unless anyone has a great idea to get the LG working it looks like I will be negotiating a return of the LG monitor

Which is a shame because I really like this monitor

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Answer 5

uktricky13 Author

Level 1

5 points

Apr 16, 2019 10:54 AM in response to Malcolm J. Rayfield

Tried this via a USB-C to DisplayPort cable this evening using USB Type C(Thunderbolt 3) to DisplayPort 4K@60Hz UHD 6 Feet Cable, Benfei USB 3.1 (USB-C) to DP Display Port Adapter Male to Male - Still exactly the same options within the Display settings :-(

I thought (was hoping) that this might fix my issue! but alas it didn't

The only difference going from HDMI is the refresh rate was 60Hertz on HDMI and using the DP cable it is 59.88 Hertz!

Otherwise same poor quality driven from the iMac

System report from the two cables connected :-)

Radeon Pro 580:

Chipset Model: Radeon Pro 580

Type: GPU

Bus: PCIe

PCIe Lane Width: x16

VRAM (Total): 8 GB

Vendor: AMD (0x1002)

Device ID: 0x67df

Revision ID: 0x00c0

ROM Revision: 113-D000AA-931

VBIOS Version: 113-D0001A1X-025

EFI Driver Version: 01.00.931

Metal: Supported, feature set macOS GPUFamily2 v1

Displays:

iMac:

Display Type: Built-In Retina LCD

Resolution: 5120x2880 Retina

Framebuffer Depth: 30-Bit Colour (ARGB2101010)

Main Display: Yes

Mirror: Off

Online: Yes

Rotation: Supported

Automatically Adjust Brightness: No

LG Ultra HD:

Resolution: 2560x1440 (QHD/WQHD - Wide Quad High Definition)

UI Looks like: 2560 x 1440 @ 59 Hz

Framebuffer Depth: 30-Bit Colour (ARGB2101010)

Mirror: Off

Online: Yes

Rotation: Supported

Automatically Adjust Brightness: No

Connection Type: DisplayPort

LG Ultra HD:

Resolution: 2560x1440 (QHD/WQHD - Wide Quad High Definition)

UI Looks like: 2560 x 1440 @ 60 Hz

Framebuffer Depth: 30-Bit Colour (ARGB2101010)

Mirror: Off

Online: Yes

Rotation: Supported

Automatically Adjust Brightness: No

Connection Type: DVI or HDMI

Adapter Firmware Version: 7.55

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Answer 6

uktricky13 Author

Level 1

5 points

Apr 16, 2019 11:52 PM in response to Malcolm J. Rayfield

Yeah suspect that is the case but I am not trying to get to 4K full resolution just 2560x1440 which the adapter happily supports to my old ACER monitor and then using the USB-C to DisplayPort also doesn't work with the LG...

Going to try speak with LG tech this morning when they open at 9am and see if they have any ideas otherwise the monitor is going back and I'll find another 24" that supports 2560x1440

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