Unofficial archive. This is a read-only, community-run archive of the Apple Support Community. It is not affiliated with or endorsed by Apple Inc.
freakywy
User level: Level 1 (4 points)

MacBook Air M5: KTC H27P3 5K monitor hi-res scaled resolutions missing with CalDigit TS5

Hi

I need help on my MacBook Air M5 with external KTC H27P3 5k monitor and CalDigit TS5.

So the problem that I have is when I use my MacBook Air M5 in clamshell mode and connect the H27P3 monitor directly to my MacBook via DisplayPort cable, I was able to get all the native hi-res-scaled resolution options just fine. see the picture below. everything works fine!


However, when I connect the CalDigit TS5 using the Thunderbolt5 cable the came with the TS5 to my MacBook Air then connect the same DisplayPort cable to one of the thunderbolt port on the back of the TS5 to the H27P3 monitor, all the hi-res scaled resolution options were gone. I even downloaded and installed the BetterDisplay app, but nothing's changed. same available resolution options in the Display Settings apply to the options in BetterDisplay options. see image below. Anybody has any idea how I can get it to work with the TS5? I really like the one-cable setup that TS5 offers.


BTW, I don't have any other devices or peripherals connected to the TS5 when I connect my MacBook with the 5k monitor.


Posted on Sep 15, 2026 4:32 PM

3 replies

PreCognition
User level: Level 6 (12,236 points)

Sep 15, 2026 7:26 PM in response to freakywy

The screenshots are useful here. When connected directly, macOS sees the H27P3 at its full 5120 × 2880 native resolution. Through the TS5, it’s only seeing modes up to 3840 × 2160, so this isn’t just macOS hiding the HiDPI choices. The 5K mode itself isn’t being negotiated through the dock.


Your M5 MacBook Air supports a single 5K display well beyond 60 Hz, so the Mac isn’t the limitation. → MacBook Air (13-inch, M5) - Tech Specs - Apple Support The H27P3 also supports 5120 × 2880 @ 60 Hz over both DisplayPort 1.4 and USB-C.

I’d try one thing before going any further: connect a rear Thunderbolt port on the TS5 directly to the H27P3’s USB-C input, using the monitor’s full-function USB-C cable, rather than USB-C-to-DisplayPort. CalDigit specifically supports connecting USB-C displays directly to the TS5’s downstream Thunderbolt ports.


If that still tops out at 4K, I’d contact CalDigit. BetterDisplay can’t really fix this if the TS5/macOS connection never exposes the monitor’s 5120 × 2880 mode in the first place. The fact that the exact same Mac and monitor work correctly when the TS5 is bypassed points pretty strongly to the dock/display link rather than a macOS scaling setting.

freakywy Author
User level: Level 1 (4 points)

Sep 15, 2026 7:43 PM in response to PreCognition

@PreCognition your suggestion worked! I did exactly it (connect a rear Thunderbolt port on the TS5 directly to the H27P3’s USB-C input) using the USB-C cable that came with the monitor. but then that leads me asking WHY? what's the difference between using a USB-C cable vs. USB-C DP cable?

PreCognition
User level: Level 6 (12,236 points)

Sep 15, 2026 8:35 PM in response to freakywy

Good question. It’s not that USB-C-to-DisplayPort is inherently limited to 4K — the TS5 supports that type of connection too.


What your test shows is that something in the particular TS5 → USB-C-to-DisplayPort → H27P3 path isn’t negotiating the monitor’s full 5K mode correctly. With USB-C directly to the monitor, that extra conversion/adapter path is removed, and the TS5 and H27P3 successfully negotiate 5120 × 2880.


Since the same DP cable works at 5K when connected directly to the Mac, I’d consider this more of a compatibility/handshake quirk with that cable through the TS5 than a limitation of DisplayPort itself.

Originally posted at discussions.apple.com/thread/256357661