CAC-1080 vs Intel 520 graphics. No signal

Updated on 06-09-2023 in Adapters and Cables
10 on 05-03-2018

I have a Lenovo laptop with Intel Graphics 520 and docking station.
The docking station features a DisplayPort.

I am using an LG 32UD59-B 4K monitor which has 3 inputs : 1x DisplayPort, 2x HDMI 2.0 .

If I connect the DisplayPort from the docking station directly to the LG monitor DisplayPort input, I get 4K60 (3820×2160 at 60 Hz).

However, I want to use the HDMI 2.0 input on the LG monitor, because the other inputs are already in use (other devices connected).

I bought the CAC-1080 adapter for this reason.

Unfortunately, I get “no signal” when I use the docking station DisplayPort out, plus CAC-1080 and use an HDMI cable to the monitor’s HDMI in. This is true both in Windows and during BIOS screens on the laptop.

The CAC-1080 adapter works fine at 4K 60 with the DisplayPort output from a GTX 960 on a desktop computer, and also works fine with the DisplayPort output from another desktop with Intel 530 graphics (built-in to motherboard). This is when using the same HDMI cable, same monitor and same HDMI input on the monitor.

The signal failure only occurs with the Intel 520 on the laptop. Because the adapter works with two GPUs and not a 3rd, I think a defective CAC-1080 unit can be ruled out. This is likely some compatibility issue. Hopefully, it can be fixed in firmware  in the adapter.

Please help. I tried looking for a support link but did not find one, so I am posting this to the forum.

  • Liked by
0 on 05-03-2018

Adding this spreadsheet of all the tests I conducted.

Clearly the monitor is capable of 4K 60 on its HDMI input – see lines 3, 7, 11.

The laptop’s GPU is clearly capable of 4K60 output also – see line 13 .

The problem is very clearly related to the adapter – line 17 . Even a passive adapter gets 4K 30 – but the CAC-1080 results in no signal.

The CAC-1080 is not DOA since it works in two cases – see lines 7 and 11 .

So I’m left with the adapter firmware bug suspicion.

  • Liked by
7 on 05-03-2018

Good day madbrain,

Which Lenovo laptop do you have?
If it has a DP output, did you try connecting it direct, without the docking in between?

on 05-03-2018

Thinkpad T460 .

The laptop has a mini DP output, but I don’t have the proper adapter for mini DP to DP to test it.

In any case, the DP on the docking station works at 4K60 when using a Displayport cable and the DP input on the monitor. That clearly shows the docking station is capable of 4K60 on its DP out.

on 05-03-2018

BTW, updated the laptop BIOS and Intel graphics drivers to the latest from the Lenovo web site, but still no change – black screen both on boot iand n Windows with the CAC-1080 in the signal path.

on 05-03-2018

Also, if I disable the “HDMI deep color” option in the monitor settings for the HDMI output, I do get a signal with the adapter in the signal path. However, it’s only 4K30, and there is a lot of flicker, about once every second or so.
While this is better than no signal at all, it is still worse than the passive adapter which gets 4K30 with no flicker – or using the HDMI 1.4 output of the docking station.

The deep color option is not well documented by LG, but from what I can tell it disables 4K60, even when using a native HDMI 2.0 GPU like my GTX 960 . Took me a while to figure out while I was getting only 4K30 when using HDMI-HDMI.

Anyway, long story short, adapter is still not doing its job on my laptop with HD Graphics 520.

on 05-03-2018

Hi madbrain,

Sounds like a compatibility issue to me between the Docking Station and the Active adapter. It is not uncommon that Active Adapters like the CAC-1080 do not work well together with other active devices like Docking Sations / Switches (etc.) in the same signal line. 
Indeed, most LG screens need to have UHD Color manullay set to “enable” to support 4K 60Hz. And please make sure to have HDR disbaled.
Did you try making a custom resolution in the Intel Graphics Driver? SOmtimes it helps to overwrite what Intel Driver thinks  is a good setting …

Shoudl be something liek this … 

–          Custom Resolution Intel Graphics Software

Making that Custom resolution in the Intel Graphics Driver should be something like this …

Open Intel Graphics Control Panel, choose “Custom Resolutions” (left bottom option) It will ask you if you wish to continue; YES
Standard the “Basic” setting is shown, click on “Advanced”, make sure you make this custom resolution for the correct screen (left bottom)
Fill in; Width 3840; Height 2160; Refresh Rate 60 ; Set Timing Standard to CVT-RB for use with TV (and for use with Monitor you can leave that on “Auto”). 

If possible please set Color Depth BPC to 8 Bit. and click on “ADD” on the right bottom of the window. Now this resolution I added to the system and can be chosen. 
Go back to “General Settings” (left top), it will show the basic options and here you can now choose the 3840×2160 resolution at 60Hz. 
(You might need to so a reboot first)

on 05-03-2018

I just located a mini DP to DP adapter cable. Didn’t think I had one, but I did.
The mini DP port on the laptop does not seem to be active at all. This is regardless of whether the laptop is on the docking station or not.

The Intel Graphics Panel does not even detect the display when using that mini DP port and hooking it up to the monitor via DP.

I even tried hooking it up via laptop mini DP -> mini DP to DP -> DP to HDMI -> HDMI cable -> HDMI input on monitor . Same issue, graphics software does not detect it at all.

It appears the mini DP port on the laptop is completely inactive. Wonder if there is some sort of switch to use it.

So, looks like the docking station is the only way at the moment.

on 06-03-2018

In my normal work environment, the laptop is face down on the docking station, and I only use the monitor or monitors that are hooked up to the docking station.

For purposes of testing, I was only hooking up a single monitor to the docking station – the LG 32UD59-B . And with a blank screen, I had no way of editing any of the display settings as you suggested.

If I put the laptop with the display up, I could access the driver settings. And then, by hooking up the monitor on DP #2 of the docking station, I could get it to work at 4K60 using the CAC-1080. However, as soon as I disabled the multi-monitor mode, ie. disabled the built-in display, the Intel graphics went back to its broken settings, and could no longer send a signal to the LG at all.

I then put the laptop face down again, and hooked up another monitor – my Asus PB238Q in portrait mode, which is physically located to the right of the LG . This allowed me to use the Intel graphics. I was then able to get it the LG to “work” in 4K50 . 4K60 still resulted in no signal. However, there is sometimes “white snow” blinking in the top left of the screen when moving windows. So it is still not really working as intended . 4K50 would be good enough for me if it wasn’t for this snow problem.

If I disable the Asus display to run the LG by itself, once again the Intel graphics switches to its default 60 Hz and results in no signal with the CAC-1080 .

It seems I just can’t manage the display settings when running the LG by itself. The driver is “too smart” and records the settings for each combination of monitors.

I think the only thing that’s really going to work for me is a properly fixed adapter. Is there any chance Club-3D can work with me to fix the firmware to make it work ?

As to docking stations causing problems, I was previously running two HP LP3065 30″ monitors at 2560×1600. I used Accell adapters to convert the DisplayPort to 2560×1600  at 60 Hz. This worked perfectly fine in Windows, though it didn’t work during BIOS time (black screen).

I would really appreciate your help fixing the adapter, as I planned to purchase several of them in order to utilize all the inputs on my two LG 32UD59-B monitors to run all 3 computers I have.

At the moment, the best I have achieved is this :
1) desktop #1 with GTX 960
DP#1 to LG 32UD59-B monitor DP input on the left . 4K60 / 10 bit
DP#2 to LG 32UD59-B monitor DP input in the center. 4K60 / 10 bit
HDMI to Asus PB238 monitor in portrait mode on the right . 1080p

2) desktop #2 with Intel Graphics 520
DP + CAC-1080 to LG 32UD59-B monitor in the center . 4K60 / 8 bit
HDMI to Asus PB238 monitor in portrait mode on the right . 1080p

3) laptop
HDMI to LG monitor on the left HDMI in . 2560×1440 at 60 Hz . Or 4K30
DP #1 to LG monitor in the center HDMI in . 2560×1440 at 60 Hz . Or 4K30

Technically, the Asus PB238 is hooked up to a DVI KVM, not directly to each computer.
Really wish there was a DisplayPort KVM that did 4K60 and didn’t cost more than the price of my two LG 4K monitors combined. If there was, I wouldn’t need to mess with any active converters …

I plan to buy another GPU with for desktop #2 to also run the LG monitor on the left in 4K60 with that computer – ie. drive all 3 monitors with the desktop. It could be either a GPU with native HDMI 2.0, or a GPU with DisplayPort paired with another CAC-1080 .

For the laptop, I would like to run the LG monitor in the center at 4K60 + Asus PB238Q in 1080p, both hooked up to the docking stations. This would entail having a working CAC-1080 adapter that can convert the DP 4k60 to HDMI 2.0 4K60 – the problem right now, and subject of this thread. Right now, the CAC-1080 adapter achieved only 4K50 with some intermittent white snow.

I know the Intel Graphics 520 GPU on the laptop with docking station cannot run both LG monitors in 4K60, as I tried that combination with straight DisplayPort to DisplayPort, and it could only manage a single monitor at 4K60 – no signal on the other DP. Otherwise I would run both if I could.

As you can see, I could possibly have as many as 3 CAC-1080 in use if they all worked – two for desktop #2 and one for the laptop . Hardly a volume customer, but still, I would own three of the CAC-1080 .

This issue really has been driving me nuts all weekend trying to get things to work at 4K60 on the laptop . If I can’t make it work reliably, I may return the LG monitors to Fry’s and sticking with my two HP LP3065 for years … Would be a shame though as I had been waiting to switch to 4K for so long, but never found affordable 4K monitors with enough inputs and a sufficiently ergonomic mechanism to switch inputs. Most monitors require going deep into menus to switch. The LG has a joystick underneath that is more usable (but still not as good as a KVM with keyboard hotkeys) . It doesn’t autoswitch input also if one input loses signal, like my HP did. On the other hand, the LP 3065 had a great input pushbutton toggle that was better than the LG joystick.

on 06-03-2018

Unfiortunately we do not have a Thinkpad T460 here to duplicate the issue you are having. What is the type nr of your Notebook? (i saw there are many different T460 ‘s out there) 
Will try to to find a way to figure this out. 
A CAC- 1070 / CAC-2070 also does 4K 60Hz from DP to HDMI but has different chip inside and might behave different. Parhaps worth a try.

Show more replies
  • Liked by