Mac Studio M5 Thunderbolt power issues.

that Dell UP3218K appears to be a full 8k display with refresh rate of 60 Hz.

connectivity includes

DisplayPort 1.4 -- which is severely limited to HBR3 mode supporting only 25.92 G bits/sec per cable.

and it does require two cables for this connection method, where each of the Left and Right half-displays is required to support essentially a double-height 4K display of 3840 wide and 4320 tall.

Unfortunately, that 3840 by 4320 half-display does not fit cleanly inside an HBR3 connection, exceeding it by about 21 percent. This requires Display Stream Compression to get a picture.

Also, connecting Thunderbolt ports to DisplayPort inputs requires adapters or cable/adpters. ¿What adapters are you using? how long are your cables?

Connecting via HDMI also appears to require adapters or adapter/cables? what kind and how long are those cables?

adapters or adapter/cables are competing Bus-powered devices. OWC states on their web site that that drive enclosure:

• Does not mount if being connected as the third bus powered device with select Mac systems, including the Apple (M4) MacMini16,11 and Apple (M4 Max) Mac Studio.

https://eshop.macsales.com/item/OWC/US4V2EXP1MT04/#specs

There's a footnote on the OWC product description page that says

"PCIe Gen 5 NVMe M.2 SSDs require careful selection and verification of manufacturer specifications due to the bus-power limits of host computers, docks, and hubs. We recommend choosing a PCIe Gen 5 SSD that consumes 11 watts or less on average during sustained read or write operations such as the Samsung 9100 Pro Series Gen 5 NVMe."

https://eshop.macsales.com/shop/owc-express-1m2-80g

hgtefla2 wrote:

Hi Grant, Thanks for your pointers - I'm reaching out to OWC support for a possible workaround. Cheers, Terry

The most obvious work-around is not possible: to supply external power to that drive.

So using another powered Hub of some description is likely to be the next best work-around.

Exactly where you apply it is not completely obvious, but you appear to currently be using stuff that is all at USB speeds, not the more expensive Thunderbolt device speeds.

If you have to buy a Thunderbolt Dock, remember that Thunderbolt-5 has higher potential speeds.

On the other hand, it is generally a mistake to buy tomorrow's promises of features with today's money.

hgtefla2 wrote:

Sorry - I forgot to add that information. The adapters are Cablematters USB-c to DisplayPort 2.1.

Those appear to be either THE best or one of the best available today. They can run up to UHBR10 at 38.69 G bits/sec, just short of the 40 G bits/sec top speed of Thunderbolt-4. That is FAR faster than the display can accept data.

But they need some USB power to do the adaptation.

Best Practice is to keep USB-C cables and DisplayPort cables under ONE meter maximum.

hgtefla2 wrote:

The HDI to Display port is an UpTab (Powered) adapter - I only get 4K with it and the Display port cables are about 5 feet long.

'Only 4K' is a limitation of the inputs on the Display.

Everything else you are using could support up to 8K with one cable.

But DisplayPort cables should be limited to at most ONE meter. Longer risks encountering Transmission errors while will cause the display to be dropped.

HDMI cables can be somewhat longer, because they use higher voltages. But HDMI 2.1 Requires certified ULTRA cables, which are different from all older HDMI cables.

hgtefla2 wrote:

Thanks for your response. The small print - I've never been good in that area :). I guess I'm going to have to get a Thunderbolt hub.

NB>> nothing you are connecting is using Thunderbolt -- it's all using USB.

Be sure to keep your wits about you as you shop, because it's easy to spend way more than you need to for capabilities you do not currently need.

¿Thunderbolt "nice to have" ?? Sure, and likely to be useful for a long time.

¿Worth twice the cost of a powered USB hub?? I don't thing so.