Resolume Forum

Running an iMac 5k late 2015 with AMD Radeon R9 M395, and attempting to run a 4k 60hz signal to the Fx4. I'm using a thunderbolt to displayport and DP to Fx4.

Ok so here's the problem: even with SwitchResX I am unable to get a good hz signal. The only 4K options are 24hz, and the highest 60hz option is 1080p. I'm getting an occasional flicker signal to my 3 projectors and this could be realllly bad for business.

Any thoughts on if its my specific graphics card? I even tried to create a custom resolution in SwitchResX but to no avail.... any help much appreciated!

How have you programmed your FX4?

Also, have you disabled SIP? If not, take a look at this link.

I have disabled SIP, yes.

Using Wall Designer I have setup my input to 4K at 60hz. Sending out to 3 outputs with SDI 1920x1200.

Sending out to 3 outputs with SDI 1920x1200.

It looks like 1920x1080 which makes sense since 1920x1200 is not an SMPTE resolution.

It sounds like your cable is the bottle neck, so the first thing I would do is make sure you have a good cable. 3840×2160@60 8 bpc (24 bit/px) requires 17.11 Gbit/s in CVT standard mode which is pretty much the bandwidth of DP 1.2 so you might want to try CVT Reduced Blanking to see if you get better results but I would make sure to buy a cable that supports DisplayPort 1.3 or 1.4.

It sounds like your cable is the bottle neck, so the first thing I would do is make sure you have a good cable.

Thanks! Will try another, better cable and see if I get results. Appreciate the quick response....