Thanks for the testing, John.

Conclusion

The i7-3770k and RX480 combination is not ready for 4K.

That is probably highly dependent on which flavour of 4K, and which codec Vegas uses to decode it (see bottom of file properties window to find out). If that Canon footage is getting decoded by mxfplug3.dll for example, it might be a lot less snappy than, for example, compoundplug.dll decoding 4K AVC footage.

Conclusion

The i7-3770k and RX480 combination is not ready for 4K.

Officially, for 4K SCS had specified an 8core system even for Vegas Pro12/13.

I have been able to playback UHD 25p with the full frame rate with an i7 2600K overclocked to 4.2 Ghz, but the system was at the limit.

In the meantime I changed my major system to i7 5960X, and that works better with UHD footage. But even with that system Vegas has clear limitations with XAVC but also other types of 4K footage. The RX card witll not help a lot for playback of pure footage really, but if you add some effects to the event in the timeline it helps.

So for UHD 50p footage I tend to work with project properties of UHD 25p. Works fine so far.

It's important when doing any benchmarking with 4K fottage to disable the option for automatically creating proxies.

Why wouldnt the gpu help in playback with 4k files if it does with HD files? I did a quick test yesterday , a 23.97 4k pro res 422 file without any plugins at best full view i get about 12fps with me 32 cores 64 ram gtx1060 system with gou turn on.. lowering down preview to good and below didnt really help much or saw major extra fps , maybe 1.5 fps max...so as is at is best case i can preview 13.5fps ...10 more to go to feel like i can edit 4k pro res..hope magix take this issue seriously with regards to playback in timeline of 4k formats, as it does hd now with no issues..so, im thinking maybe the rx480 will get me extra 4-5 fps more?

OK... the Nvidia card was replaced today and don't have the info compiled to post yet, but the AMD was faster rendering than the Nvidia with the red car test. I did not record the actual with the AMD as we were doing the tests at the pc shop just to test the new card but all 3 tests rendered faster with the AMD. I will retest the AMD with the red car sample and post those results soon... but what was even more important to me... this morning, prior to having the card swapped, I was trying to render a purchased template and with the Nvidia card, it crashed 3 times in a row... Each time it would get stuck on frame 944... sit there for several minutes and then crash. Out of frustration, I deleted the template and then disconnected the pc and took it in to get the card replaced. After I got home with the new AMD card in place, I thought about that template and checked my deleted bin and it was still there. I restored it to my desktop and re-rendered the svg file and it ran flawlessly and completed in 1.28 minutes. I re-rendered 2 more times and it rendered perfectly each time. Definitely super happy with this AMD card... and they rebated me $400.00... "Sweet Deal"

Another report on my new AMD RX - 480 card. Recently I purchased a template from Vegasaur... The name of the template was Photo Wall. I replaced images and rendered and it took almost 4 hours to complete. I contacted Vegasuar tech support and inquired about the time it took to render... Their response was "Photo Wall is the most complex of our templates with plenty of effects and several nested projects. Each nested project contains hundreds of animation keyframes. This affects the rendering time".

I just rendered that same template again with the new AMD and time was 2:06:05 min's to complete. Same identical settings too. Thanks Nick!!

Thanks for the report Mike. This is the first direct GTX 1080 vs RX 480 testing I've seen so it's important, and glad to know that we've not been misleading people by steering them towards the AMD card.

Re. Photo Wall, are you saying that it was 4 hours with the GTX 1080 installed and GPU acceleration of video processing enabled?

Yes... it was 5 hrs with original PC, almost 4 hrs with new PC & nvidia card and slightly over 2 hrs with AMD card. And all renders were with GPU on.

But like they told me, it was their most complex template with hundreds of key frames so very long render time too I guess. Definitely faster due to the AMD. Now that's with VP. Wonder how it would do with premier pro or video pad or several other editing software on the private market today?

Nearly 2x improvement with RX480 over GTX1080 is more than I expected! It more or less settles the discussion, unless alternative or future Nvidia drivers improve OpenCL.

[ Edit: There is some discussion of this comment here: https://www.vegascreativesoftware.info/us/forum/gpu-render-speed-rx-470-qsv--105337/#ca651459 ]

Yep... When I 1st talked to the tech's about changing out cards they said I would be downgrading and thought this would be a mistake... All 3 of them watched as I did the tests and they were very surprised when it out performed the Nvidia card. and want to make it clear that this does not mean the Nvidia card is inferior in any way... just that AMD is a more compatible card for VP... at least for my personal hardware. Thanks Nick and yes, this is resolved

Thanks for the test Mike.. how about the playback in timeline, did you notice more fps or smoother playback with RX480 compared to the 1080 ?

Note that rendering time in this case is effectively a measure of timeline performance, since GPU-accelerated rendering is not supported by either card. They're only supporting GPU acceleration of video processing. If that doesn't make sense, read this.

Sorry Nick but did not watch the specific fps as it rendered. I started the render, watched for a few minutes and walked away as I knew this project would require some time to complete, based on my past experience with that template... But I did notice the playback was smoother with the RX-480.

I know we said this is now resolved but have to share this new discovery with everyone. One of the other issues I was experiencing with the Nvidia 1080 card was trying to edit 4K (MFX) clips. It was very jerky, ran at least 4 to 5 seconds behind the audio (real time) which made precise editing very, very difficult. I just opened one of my 4K clips I video'd today and it now plays beautifully in real time!!. No lag time at all and super clear in the preview window. I couldn't believe it. I had to look in the project media bin to ensure it was an MXF file... and it was... and just to be sure, I tried a few more clips before posting this new info... and all with the same results!!... I love this new card!! :)

I did not read to the complete thread, but I would like to add some of my experience with another type of high end NVIDEA card (TITAN X). Let me tell you I build my own computers for a very long time and working in telecom software debugging since 1985. I use my PC for gaming and video editing so not going for Nvidea is just not done if you are a gamer in the present 2016. (I had ATI in their heydays in the past, and AMD processors) so I am not biased to any processor or videocard. Currently I have a bit aging i7-4770k, 16 GB mem and  and a GTX TITAN X 12GB GDDR5 NVIDIA (Maxwell, not the new TITAN X Pascal). At a certain moment I had a reproducible vegas pro 14 crash by letting the PC just repeating in the preview window some 50P HD file with a newblue PIP effect. Sure enough muting the plugin track and it did not crash. At times Vegas had additional (unrelated to the reproducible crash project) crashes. So I started to methodically change various settings to see if the reproducible crash could be solved. By methodically I mean only one item setting change at any time, and put back the setting if this was not the culprit. Only after putting the Dynamic RAM preview to zero I had stopped all crashes. I am running now without crashes for weeks now (I use a lot of newblue plugins). I have no clue why I had to put this to zero as I am not using pre-rendering (at least not intentionally or manually or that I know off). Ok but I am deviating. Using the Nvidea Titan x makes the edits snappy and fast - I do not seem to miss Dynamic RAM preview (or am I wrong?). Anyway I am very happy with vegas 14. Not so with magix pro x I also own, and which is going downhill fast with crashes, and cannot cope with most newblue OFX plugins.  

Only after putting the Dynamic RAM preview to zero I had stopped all crashes.

Thanks for sharing your experience bitman, I'm an AMD RX470 user, and many times I also had rendering 'stucks' problem in the middle... I thought it was the 3rd party titling application, but finally found if I set DRAM to 0, the problem gone... So sometimes the DRAM can help, but it can also bring disaster...

DRAM?... Where is this setting? I would like to try it and see results.

If you use the forum Search function with the search argument "Dynamic RAM preview 0", you'll find waaaaaaaaay more than you ever wanted to know about the subject.

Great... well so glad I found this forum. All of my issues are now resolved. Thanks so much for all the advice, info, suggestions and ultimate resolve of my recent issues.

You should really run some test on the this setting Dynamic Preview to 0 before settling on that as the solution. I found a Zero setting to actually increase render times. I found a default setting to work the best. I rarely use the RAM Preview, except when doing motion graphics previews.