How far should I push ram? Just did an upgrade and WOW what a difference!

[baserock love]

Just putting this out here and also asking a question in case anybody has dealt with this issue I have. 

I had 32 gigs of ddr4 running at the default 2133 mhz for sometime and photoshop as far as performance (With one glaring issue, see my other thread i just posted.) was fine on the 4k or so canvas sizes i worked on. recently I started getting print commissions that require as much as a 20k canvas which was utterly unworkable.  I'm working on one now and have it at about 8k in which i'll do 98% of the painting and just touch it up at native resolution which is about 20k but even at 8k the brush lag was pretty bad with some of my custom brushes, REALLY slowing down my workflow. 

I recently finally got another 32 gigs of ram for a total of 64 and this made a HUGE difference but brush lag with my custom mixer brushes i use was still pretty noticable but at least workable and only minorly slowed me down. 

After reading that ram speed makes basically no difference in ps i was curious and after a lot of headaches i finally got my ram running at 3200ghz totally stable and I don't know what people are talking about because it made the brush lag again noticably better, sometimes nonexistent on this 8k canvas i'm working on.  I'm just mentioning this because despite what people have said elsewhere i did clearly see a difference and it's worth looking into if you're having brush lag on big documents. 

So my question is, considering PS BARELY uses gpu/cpu  but is an absolute ram hog (Gpu/cpu get about 5% utilization most of the time whereas ram is getting 70ish percent) would upgrading to 128 gb of ram allow me to work natively on gigantic documents like 20k? Is that even worth doing?

What setups do people have for gigantic print poster size documents to get them to run smoothly and paint on them? 

[didiermazier]

The more the best

😉

[baserock love]

So as long as cpu/gpu utilization is low is that how ps works? Just keep throwing ram at it and you can work in bigger and bigger documents?

[davescm]

The biggest impact is scratch disk space and speed. No matter how much RAM you have, I have 256GB installed but did not install that for Photoshop, Photoshop is going to swap RAM and scratch disk as you work. Beyond around 64GB RAM, a fast NVMe scratch drive with plenty of space (500GB +) will have the biggest impact.

In addition, make sure you are not working at unnecessarily high pixel counts. The thing about large posters etc is that they are viewed from a greater distance. So whilst you view an A3 size book spread from 20 inches or so, a 15 foot poster is viewed from several feet away. Therefore the ppi requirement for the large poster is much smaller than that for the book-spread. Printing the large poster at 300ppi is wasted as at viewing distance human eyes just can't resolve that level of detail. There is a formula for ppi required based on viewing distance which I will post when I get back to my office.

Dave

[baserock love]

Ok, that's good to know! i might look into bigger nvme drive to use for scratch space just dedicated to ps. I'd love to see that chart tho. That said,t his latest one is gonna be a big game mat for a table so it will be viewed pretty close.

[D Fosse]

Dave is absolutely spot on, I couldn't have said it better 🙂 You were probably low on scratch disk space, in which case more RAM might feel like a temporary improvement.

Don't overclock RAM. It's at the expense of stability. As for brush responsiveness, the GPU plays a part in that too. Under normal circumstances, with a properly balanced system, brush responsiveness should not be a problem.

Ppi requirement is always overestimated. Even the standard book/magazine "standard" of 300 ppi is usually misunderstood. It's not a minimum limit. It's a theoretical maximum limit, it can be lower without any problems.

And it's not even a sharpness parameter. It's a smoothness parameter. It's based on a halftone screen frequency of 150 lines per inch, which is usually used for books/magazines, and if you double that number, it is no longer possible to discern individual pixels.

Go check a standard HD desktop monitor, which has a native screen resolution of around 95 ppi. How close do you need to go before you can see pixels?

[baserock love]

So i don't think i'm low on scratch disk space, the file i'm working on is about an 8k canvas, maybe 15 or 20 layers which i'll reduce as i progress with the project till it's eventually a single layer. the scratch disk set is a sata ssd, pretty standard speeds for an ok standard drive. 

Note that the brush lag i'm experiencing is ONLY with the mixer brush which i only really get with large canvases and that's only when i have it set to sample on all layers (They really need a "Current and below" option for this tool btw.). Normal non mixer and simpler brushes do not have this lag, my favorite custom brush i've made which is my primary painting brush IS a mixer brush. 

That said i just did an experiment and set my decently quick nvme as the scratch disk which has about 140 gigs free on it (The psd file isn't even 1 gb currently.), this should be MUCH faster than the sata ssd i was using before. I saw no discernible difference in the brush lag. 

I'm now starting to wonder if this is more of a limitation of the software rather than my hardware as with my current setup ram/cpu/gpu have pretty low utilization so maybe i'm chasing my tail here.  IF there is a way to work with the mixer brush tool on 7k to 10k documents and reduce the brush lag to a minimum i'd love to know. That's really what my main dillemma is here currently.

Thanks for the tips on resolution. FOr this print stuff i've done a bit of testing. For one job i did most of the illustration at a lower resolution, once i flattened the image iwth it all painted i increased it to native 300dpi resolution and then just went in and refined all my edges and this made the image look really crisp once i saw the finished product. 

As for running my ram at a faster speed, my system is stable. If that changes i'll put it back to default but currently it's not an issue. 

Thanks for the reply!

[baserock love]

Oh I forgot to mention the current ssd i use for my scratch has 320gigs free so space shouldn't be an issue for a sub 1gig file from what i've read here.

[davescm]

The formula for ppi is 

ppi required = 6878/Viewing distance in inches.

If you are interested in where that comes from :

A good human eye can resolve 60 line pairs per degree i.e. pairs of black and white lines.  So in half a degree we can see 60 single lines.

Simple trigonometry means that the width containing those 60 lines can be calculated by:
               Width of 60 lines = Viewing distance x tan(0.5°)

Knowing the width for 60 lines (or pixels) , can be used to calculate how many of those lines (or pixels) can be seen in 1 inch by using 60/Width of 60 lines.

So putting those together gives:

60/(Viewing distance x tan(0.5°)) = 60/(Viewing distance x 0.0087269) = 2/(Viewing distance x 0.000291)    

Or

6878/Viewing distance

Dave

[Trevor.Dennis]

Absolutely agree with that.  You only have to look at the size of the Photoshop temp files on your scratch drive to know how crucial the speed of those drives is.  I have 64Gb on my one year old i9 13900K system, which is the same as my last system, and I didn't bother getting more RAM because my last system never seemed to use anything close to the alocated RAM.

I do remember a thread on this forum at least ten years ago, with Development Team member Chris Cox.  Someone asked Chris what the limiting factor was for Photoshop on the then state of the art systems, and he said RAM speed.  This was probably before the first SSDs, so we were using HDDs with maybe 120MBs if you had a Velociraptor or similar.   The best NVMe drives nowadays are better than 10,000MBs sequential read and write.  That's 80 times faster!  So it's hard to think that moving that 20 or 30Gb temp file in and out of RAM is not going to be the limiting factor.  I have no idea why Photoshop does not make more use of available memory.

If you are using Windows 10 or 11, but especially 11, you can use the Task Manager > Performance tab and Resource Monitor to get actual feedback on your system bottle necks.

[Trevor.Dennis]

https://www.harddrivebenchmark.net/ssd.html

[westdr1dw]

Although the feedback response to the OP are very insightful. Thought I may add to the discussion from personal experience in PS. As Trevor mentioned in Win performance monitor is highly recommended to view on watching the resources consumed in the process. I have an I9 9th Gen CPU, 32 Gb RAM 3200, 2 TB NVMe, and a RTX 2070 graphics card. On normal day the GPU usage is most noticable. RAM runs between 12 - 16 Gb. Depending on the image CPU peaks on occasion. I have a lot of space on the drive so no real detectable bottle necks at present. With the price of RAM would not consider anything under 64Gb on new builds. Then again I am not doing billboards.

[Trevor.Dennis]

With the price of RAM would not consider anything under 64Gb on new builds. Then again I am not doing billboards.

By @westdr1dw

It depends so much on what you are doing.  As mentioned, I find 64Gb is more than enough for Photoshop, but I suspect that 32Gb is less than optimum.  On the other hand, one of the other responders in this thread is a big user of Blender and the Substance apps, and has a whopping 256Gb RAM, and IIRC, 24Gb of V-RAM!

[baserock love]

So that's the thing, when i was on 32 gigs, i would monitor system usage and it would be on my larger files about:

3% cpu
1 to 5% gpu

70% ram
Keep in mind this would also be while running chrome to listen to news and stuff on youtube while i worked and chrome uses a big chunk of ram but not as big as PS.  

Now that i'm up to 64 gigs i get the same allocations but it uses about 40% of my ram so there doesn't actually seem to be a bottleneck anywhere there. This is why i'm wondering if a faster scratch disk will solve the mixer brush lag on larger canvases with 10+ layers. 

At the same time i set my 132gig free nvme drive (Old one and not great but certainly faster than the sata ssd i currently use.) and i saw no didscernible difference in the brush lag. 

What i DID see a difference from was increasing my ram to 64 gigs and my ram clock speed to 3200mhz. 

I really am wondering though if it's just a software limitation with this particular tool, the mixer brush. NOTHING is maxing out on my system when painting on these larger canvases with it so i might just be chasing my tail here.