I did some testing to find out what would happen in a couple of different scenarios ...  Here's what I found out: What would happen if I try to add a photo in the LR-CC desktop application that I’ve already added to LR-CC on a mobile device? The LR-CC desktop application recognizes the duplicate during import.  The duplicate will be greyed out, without a checkmark, and on mouse-over will say “Previously Added”. What would happen if I try to add a photo to LR-Classic that I have already added to LR-CC? If you’ve activated “Sync with Lightroom CC” in LR-Classic, then LR-Classic should identify this photo as a duplicate, and it will be dark and not selected when you attempt to import photos from the card or folder where that image resides.  (Note: If the image is renamed, it will not be identified as a duplicate)  What would happen if I try to add a photo to LR-CC that I have already added to LR-Classic? If that photo is in a collection in LR-Classic that is synched with LR-CC, then LR-CC will not allow you to add the photo and instead you’ll get a “Skipped importing duplicate” message.  (Nice!) However, if that photo is not in a synced collection in LR-Classic, but you’ve activated “Sync with Lightroom CC” in LR-Classic, then the LR-CC photo would become a virtual copy of the existing photo in LR-Classic, but the actual image itself will not be duplicated.    I’ll explain this in greater detail below … In LR-Classic, after syncing with LR-CC, the photo would appear in the “Synched Duplicates” collection in the Catalog menu.  If you single-click the image, then go to “All Photographs” in the Catalog menu, the duplicates will be highlighted.  The photo from LR-CC will become a virtual copy of the photo that was already in the LR-Classic catalog.  In this case, the original image will not download to the LR-CC download location on your computer, since you already have the image on your computer.   If you delete the synched LR-CC photo in LR-Classic, which is considered a virtual copy in LR-Classic, the photo will be deleted in both LR-Classic and Lightroom-CC.  Undo delete will not bring it back in LR-CC but it will bring back the virtual copy in LR-Classic. If you delete the LR-Classic photo, that photo will be deleted, AND the synched LR-CC photo will be deleted from both LR-Classic AND Lightroom-CC! Again, undo will not bring it back in LR-CC.  Your best option is to either do nothing if the photo has different edits applied to each version and you want to keep both, or keep only the LR-Classic photo and put that in a collection that is synced with LR-CC.  If you prefer the edits of the LR-CC photo, copy/paste the edits from the LR-CC photo to the LR-Classic photo before you delete the LR-CC photo.   If I’ve activated “Sync with Lightroom CC” in LR-Classic, where are the files downloaded? The images are downloaded to wherever you specified in LR-Classic Preferences à Lightroom Sync.  If you want to move the images to another folder after they’ve downloaded, you can do so in Lightroom Classic, but not outside of Lightroom or else it won’t be able to find the images.  Changing the LR-CC downloads location will only impact future downloads.  It will not move or impact the images that have been previously downloaded to another location.  ... View more

Sorry for the delay, I missed your reply. yes, I think that would give you good performance.  It’s recommended to keep the media and the scratch/cache files on a separate drive from the O/S and programs, but I don’t know how big of a difference it actually makes.  Puget Systems, linked above, says it makes a big difference.  I do know that everthing is much quicker on an SSD though. If it offers you the option of getting a second or third HD, that’s good.  That means you could always buy an SSD down the road and plug it into one of the spare SATA and power connectors.  It’s easy to do.  A quick YouTube tutorial would show you how.  SSD drives and regular HDDs connect the same way.  ... View more

Thank you for your reply.  Let's forget about Lightroom Classic for now to make this less confusing ... My goal is to avoid duplicates.  What happens if I edit a select few photos on my mobile device in LR CC, then I get home, insert my SD card, and transfer ALL photos from the SD card onto my computer in the appropriate folder (e.g. Iceland) and into the LR CC catalog?  Would the originals of the select few images that I've already edited in LR CC on my mobile device become duplicated?  (One file in my Iceland folder and one in the LR-CC synchronized folder)  Would they also be duplicated in the LR-CC catalog or would LR identify that the image is already in the catalog when I'm importing?   In summary ...  What's the best organization method if I'm going to be editing a few photos from my SD card in LRCC on my mobile device and then transferring ALL photos on that SD card onto my computer when I get home? ... View more

I would put the O/S and applications on the 256gb ssd drive and put the media, cache, scratch and other project files on the 1tb SSD.  I dont know how much of a difference that would make versus what you proposed but that’s what Puget Systems recommends.  https://www.pugetsystems.com/labs/articles/Adobe-Premiere-Pro-CC-2015-4-Storage-Optimization-854/ ... View more

Which customization of the OptiPlex 7960 are you looking at?  I just looked at the one with an Intel i7-8700 6-core cpu, 16GB ram and 256GB NVMe drive.  The problem is that it’s advised to have multiple storage drives and that’s not listed as an option, so I don’t know how many drives can be connected.  At a minimum, you should have an SSD for your O/S and programs and all of your media on a larger capacity SSD or NVMe (500gb+) or a larger (and cheaper) hard drive.  ... View more

You’ll really want a minimum of 16GB RAM.  i think that the CPU would be okay and the GPU would be okay.  Its also very important to have two SSDs, one for O/S and Applications and one for everything else.  If it comes with a 1 TB HDD, that’s fine for long term storage, but make sure you can add additional disk drives.  ... View more

Thank you for this explanation...  But I wonder why Adobe doesn’t take better advantage of a discrete GPU for h264 decoding.  If I open any 4K h264 videos in the Windows default TV & Movies application, I can see that it’s utilizing my GTX 1060 and as a result I have perfectly smooth playback.  ... View more

What is your CPU % utilization and GPU % utilization when playing unrendered h264 video?  When my integrated GPU was disabled, Premiere Pro mostly ignored the GTX 1060 during playback and relied heavily on CPU.  This causes the need to work with proxies or to constantly render.  It was only during rendering, adding special effects and exporting when I saw the GTX utilization spike.  Everyone keeps saying that is normal, that Premiere Pro doesn’t use the GPU for playback, BUT that does not appear to be the case because when I enabled my integrated Intel GPU, Premiere began using that GPU heavily for playback and CPU usage went way down.  That is why I think this is an issue.  When my integrated GPU is disabled, why isn’t Adobe utilizing the dedicated GPU for playback like it utilizes the integrated GPU when that is enabled?  ... View more

I have an interesting update to share ...  Previously I only used the GTX 1060 6GB, because why would I bother hooking up any of my monitors to the integrated Intel HD Graphics 530, right?  But as I previously posted, Premiere Pro didn't seem to use the GPU much and would blast my CPU at 100% usage, requiring me to constantly render in/out to get smooth playback of the timeline.  Well, I tried hooking up one monitor to the GTX and one to the integrated graphics and then tried playback in Adobe Premiere Pro ...  And what do you know?  Now I can play unrendered 4k h264 footage and my CPU utilization doesn't go above 30%, the Intel 530 utilization is at about 60% and the GTX sits at about 6%.  If I play footage that I previously rendered with the GTX, usage on the GTX goes up to 15% and Intel usage goes down to about 15%.  Proof if you needed it that Premiere Pro works better with integrated graphics than more powerful discrete graphics cards.  I'm shocked that Adobe hasn't fixed such a big issue.  I guess I'll sell my GTX 1060 to a gamer. ... View more

You will see a nice boost in performance if you move your media onto the SSD and just use the HDD for archiving.  It's best to have your O/S and applications on one SSD, and the active media, project files, media cache and scratch on another SSD.  (Or split that stuff up on multiple SSDs)  With your current configuration, like Neil said, using proxies may be your best option, so check out a tutorial on YouTube if you're not familiar with that process.  Or, just keep rendering in/out as you go.  4K is just a lot for any computer to handle. One more option: download and install Adobe Prelude.  It should be part of your Adobe Creative Cloud subscription.  I can't explain why, but playback is much smoother in Prelude than Premiere, so you can do the majority of your work in Prelude like setting in/out points on your clips and putting together a timeline (called a rough cut in Prelude).  Then export the rough cut into Premiere Pro, drag it onto the sequence, render it, add special effects and make any other adjustments needed, and export.   ... View more

You're not alone ...  Same issue here with the GTX 1060 6GB, except my computer can only recognize one GPU, so my CPU gets blasted during sequence playback while my GPU is barely used.  (And yes, I have CUDA enabled)  I have also seen this issue discussed with other NVidia graphics card.   Sadly, I have not found any solution to the issue, so it appears for now that a GPU is not a very good investment for improving performance in Adobe Premiere Pro! ... View more

I actually just did this upgrade, going from 16GB memory to 24GB memory, and I did see a modest improvement in performance.  However, if you don't see memory utilization at or near 100%, don't waste your money  I did the upgrade because I was maxing out my memory.  I also just upgraded to an SSD for storage of my media, cache, project files and scratch and saw a bigger improvement in performance from that.  Cheaper too.  (Previously I worked with media on my HDD and kept everything else on the O/S SSD) Dell XPS 8900 Intel i7-6700 CPU @ 3.40GHz  (6th Gen) 24GB DDR4 Memory at 2133 MHz GeForce GTX 1060 6GB Samsung 850 Evo SSD - O/S and Apps Samsung 860 Evo SSD - Media, project files, media cache, scratch Seagate Barracuda 1TB 7200RPM, 64MB Cache - Long-term storage ... View more