Let me explain what is happening...
The Intel HD Graphics engine in your processor supports three outputs. Each of these outputs can be individually configured to support one of three protocols, DisplayPort (DP), Embedded DisplayPort (eDP) or HDMI:
- DP- and eDP-configured outputs are compliant with the DP 1.2 specification. This means that they are capable of supporting a 4K monitor at up to 60Hz. They can even support HDR if a 7th gen or newer processor is being used. Now, using a really good quality dongle, it is possible to convert one of these DP outputs into a HDMI 2.0-compliant output - again with 4K support at up to 60Hz and even including HDR support. [ASIDE: dongles supporting HDR appeared on the market only very recently. If you are looking for one, make sure it's specification says that it supports HDR. If it doesn't specifically say it supported HDR, it likely doesn't]
- HDMI-configured outputs are only compliant with the HDMI 1.4b specification. This still means that they can support a 4K monitor, but only at up to 30Hz (and I don't think HDR is supported). What manufacturers sometimes do is configure the processor to generate a DP output and then include on the motherboard a conversion chip, called an LSPcon, to will convert the output from DP to HDMI compliant with the HDMI 2.0 specification. Alas, your motherboard does not include one of these chips, so you are stuck with only 30Hz output on the HDMI port.
So, I have provided you with an overview and explained one of the two issues that you are seeing. To address the other issue, I need some additional information:
- Are you using a monitor with a DP input? If so, you *should* be able to do 4K at 60Hz with HDR.
- Are you using a dongle or a cable that converts the DP output to HDMI? If so, then you likely need a better dongle and/or a better cable to get to the desired results.
Hope this helps,
thanks Scott. Yes I'm using a converting cable DP to HDMI and rather long at that (3m) I expect that is the culprit.I'll leave it for a future suss and live with what I get for now.