Does more system RAM (like 128GB) matter when working with complex high resolution files?

[loco27057486xady]

I am in the process of upgrading my current AM4 setup to AM5. New cpu, memory, videocard, everything. It's going to run Windows. I want to be sure these upgrades benefit Photoshop as much as possible. 

I often work with very large resolution files. Think photos from an 61MP camera, often multiples of these stitched, and then also with several smart layers of edits. PSB files up to 4-5 GB sometimes. And I want to build a somewhat future-proof system, so the file sizes might even increase.

Does Photoshop benefit from simply a huge amount of system RAM? Like, would 256GB ram be better than 128GB, for example? I currently have 64GB in my system and it seems like sometimes it's a limiting factor. Photoshop gets really slow, starts buffering (I suspect) etc. I want to mention I use intensive plugins like NIK and Topaz, so this could also be a CPU limitation perhaps.

Basically, what I want to know if it is useful to consider future RAM expansions while thinking about my next build? Like, get a 128GB kit now and perhaps in the future expand to 256GB. Or is this way overkill for Photoshop and is the amount of RAM meaningless after like 64GB?

[Kevin Stohlmeyer]

@loco27057486xady more RAM and GPU is always a benefit and not meaningless. This has a direct impact on processing speed. If you are working with files as large as you state - I would be maxing out RAM and GPU now. 

[D Fosse · Accepted solution]

It doesn't hurt, but the really critical component here is the scratch disk. That's where you see real-world performance impact.

There is no such thing as "enough RAM" with Photoshop. The total memory requirement will exceed any installed RAM, no matter how much you have. So temporary working data are always written to disk, aka the scratch disk.

For efficient operation with these file sizes, you should make sure to have at least 500 GB free space for the scratch disk. For big composites you might need even more. The scratch disk contains all history states for all open documents, plus some overhead. Each history state can potentially add the full uncompressed file size.

Think of RAM as a fast access cache to the scratch disk's main memory. RAM only holds the most current data.

In the old days, with slow spinning drives, this was a major bottleneck. With todays crazy fast NVMe's, it's not so critical. I'm sure RAM is theoretically faster, but in practice the bottleneck has been all but eliminated.

[davescm]

I have 256GB RAM here and I've never seen Photoshop use it (I installed it for physics simulations in 3D applications not for Photoshop). As D Fosse states above, the scratch disk is used no matter what RAM you have and a large space on a fast M2 NVMe drive will be the most benefit with large files.
Dave

[loco27057486xady]

Thanks everyone for the replies. The information about scratch disks is very interesting, I never gave that too much thought. Seems I have to look more into this. 🙂

[Conrad_C]

I often work with very large resolution files. Think photos from an 61MP camera, often multiples of these stitched, and then also with several smart layers of edits. PSB files up to 4-5 GB sometimes. And I want to build a somewhat future-proof system, so the file sizes might even increase… would 256GB ram be better than 128GB, for example? I currently have 64GB in my system and it seems like sometimes it's a limiting factor. Photoshop gets really slow, starts buffering (I suspect) etc. I want to mention I use intensive plugins like NIK and Topaz, so this could also be a CPU limitation perhaps.

By @loco27057486xady

If you’re editing 4–5GB documents then it’s reasonable to consider 128GB RAM or more. But yes, there is a point of diminishing returns, and the cause of a slowdown is not always obvious. So to spend the right amount of money in the right place, try to analyze for bottlenecks using Task Manager. When Photoshop is getting slow, open Task Manager and look through the sections. Look through CPU, GPU, memory, storage… See which system resources are operating at their limits, and which are not, so that you are putting your money in the right place.

CPU. Photoshop typically won’t use all CPU cores constantly like a video editor, because it’s editing only one frame. Some features can max out the CPU, but only for short periods. So the CPU is usually not the problem unless the computer is old, where the CPU has relatively slow single-core performance compared to today.

GPU. Photoshop might not tax the GPU for most operations, but specific features are very dependent on GPU performance, and could resuyt in a bottleneck with a weaker GPU. Some of the features that depend the most on GPU performance are the newer ones that use machine learning/AI.

Storage. If you’re using SSDs they’re faster than Photoshop needs most of the time, for basic I/O. But storage performance is actually more critical for memory usage, see below…

Memory. What does the Memory graph look like in Task Manager? Is it always filled, or usually not filled? If it’s always filled then more RAM could be a good idea. If it’s not typically filled then the bottleneck is somewhere else, and buying more RAM may not make any difference.

For Photoshop, memory usage is really about its Scratch Disk feature, with RAM being a sort of fast cache for that. Because of that, the Scratch Disk(s) assigned in Photoshop preferences should be both as fast as possible and as large as possible. A slowdown could be caused by a scratch disk being too slow (like on a hard disk drive instead of a solid state drive), or too small (so that the volume runs out of free space).

Also, in Photoshop, check the Efficiency indicator in the Status Bar. The Adobe Help article “Optimize Photoshop Performance” says…

If the value in the indicator is below 100%, Photoshop has used all available RAM and is using the scratch disk, which slows performance. If the efficiency is less than 90%, allocate more RAM to Photoshop in Performance preferences. Or, add more RAM to your system.

(If any Mac users are reading this, you can do the same analysis; the Mac equivalent of Windows Task Manager is macOS Activity Monitor.)

[frazzlesnap]

So.... if I maxed out my system's memory at 2TB, that would be pointless? I bet I could set up a ramdisk in that case, and bypass my ssds entirely.

[Conrad_C]

Again…none of us can know whether adding any amount of RAM will help or not, until we can see, from looking at the readouts, if RAM is currently a bottleneck.

What do the Photoshop Efficiency indicator and Windows Task Manager, Memory graph say as you edit your most demanding Photoshop documents? You can post screen shots of them for us to look at (use the Insert Photos button in the post editor toolbar instead of attaching, then we can see the screen shots inline).

[frazzlesnap]

I'm at my day job right now, so I don't have access to that system. My ram use is actually quite low, maybe hitting 38-60% for Photoshop, at maximum, out of 256GB. I'd like to stop using a physical scratch disk, if possible, because of the detrimental effects of performing lots of write operations for a standard nand ssd. In this case, an 8TB RAID10 of two HighPoint SSD7505s with 4 2TB Seagate Firecuda 530s each. I've had this array for about 3 years, and the device writes are piling up. I bought a 400GB Intel DC 5800x Optane drive to serve solely as a scratch disk about 2 years ago, because the DWPD limit is 100, instead of .7, but I like the additional speed of the RAID10 array, and really like being able to have more history states. I should have spent more to get at least the 1.6TB Optane drive. Live and learn.

[D Fosse]

@frazzlesnap  @loco27057486xady 

Everything is always written to the scratch disk. The complete record of the document is in the scratch file. 

Then whatever is needed for current operations is held in RAM. 

Also note that some advanced functions like many of the new AI-based operations rely on the system pagefile for temporary storage during processing, until returning the output of that operation. Again, sufficient disk space is needed.

Finally, there's the GPU, performing operations called by Photoshop. A discrete graphics card will have its own on-board VRAM, while systems with an integrated GPU will use shared system memory. Either way, this too will go to the system pagefile if physical memory runs low.

So it's a pretty complex situation, and as with everything else, what you want is a balanced configuration. Lots of RAM won't help you if you run out of disk space. Lots of disk space won't help you if the system chokes on RAM. You need to have reasonable amounts of both.

I don't think there's any reason to go overboard with RAM. My own two desktop machines have only 32 GB, and they handle everything I throw at them with ease. I also use a 60MP camera and with composites and layers, file sizes are regularly up to 10GB or so. But I do have gen 4 NVMe as scratch disks with several TB available.

I'm going to build a new machine later this year, and then I'll probably go for 64.

I'd like to stop using a physical scratch disk, if possible, because of the detrimental effects of performing lots of write operations for a standard nand ssd.

By @frazzlesnap

What people generally don't think about, is that all your applications and the operating system write to your user account constantly. It's in constant use.

[frazzlesnap]

@D Fosse 

You always make excellent points. My system used to run without a page file, but I enabled a 32GB or so one on the Optane drive, since I've been using the array for a scratch disk. I think my only potential bottleneck is my cpu's single-core speed. It came out in early 2022, and wasn't at the top of the charts even then. I got a Passmark score of just a bit over 3300 with a single core, and just shy of 70000 with all 24. I can't afford to build a new system right now, seeing as how I always seem to go with HEDT parts. I have fever dreams of building a 9995wx system eventually, or even dual Epyc 9575Fs for decent single-core and very good heavily-threaded tasks...

I'll stick with 256GB for now.

[Trevor.Dennis]

My last system had 64GB and never came close to using it with Photoshop, so I saw no reason to put more rRAM in my current system.  I've got two small files open in Photoshop at the moment, and I have restarted it a couple of times today.  This is what I am seeing in my primary scratch drive.  That's 60GB of data that Photoshop is reading and writing to, so Like @D Fosse  said, the speed of your scratch drives is crucial.

10 to 15 years ago an HDD might do 100 to 120MB/S.

I knew that m.2 drives were managing 10kMB/S, but I just found this.  That's > a hundred times faster!  

[frazzlesnap]

This is a photo I took of my RAID10 about 2 years ago, before trying to optimize it. Unfortunately, I've encountered serious issues with the SSD7505s since then. I'm embarrassed to post a current screen capture, but I'll get one when I go home tonight. I've been dealing with HighPoint tech support for about two years over my transfer rate issues, and they're super nice people, but nothing has helped in the slightest. Of course, if you aren't using the same queue depth, sample size, block size, etc. it's all apples-to-oranges.

[Trevor.Dennis]

That's a BIG number.  How many drives in the array?

[frazzlesnap]

I have 8. Again, it is not as fast as I was expecting. I've since improved some of those rates, but the overall picture is that I'm getting about 60% of what Seagate and HighPoint implied I should get with this setup. Oddly, during testing as a RAID0, my numbers weren't much better for writes. I have to have redundancy, so RAID10 is my favorite.