new iMac27" RAM enuff?

8gigs should be enough. I have a 2010 MBP with 8gigs and have no problems with PS CS6.

Also, some of the PS filters use the graphics card and videoRAM for some processing tasks. So even if you got the "base" model with 512k of videoRAM, you'll be fine.

Bending Pixels said:

Also, some of the PS filters use the graphics card and videoRAM for some processing tasks. So even if you got the "base" model with 512k of videoRAM, you'll be fine.

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Not the majority of them. At 8GB you're still using scratch disks. I'm a little confused by the use of Bridge rather than Lightroom. I thought every wedding photographer used Lightroom. As far as I know, Lightroom has yet to implement OpenCL. Capture One uses it now for certain functions. I haven't tested the difference, and I don't know the list of supported gpus there. The OP would need to better describe where the machine lags to really know if they'd benefit from more ram. Those programs are memory hungry, as is Mountain Lion. Lion was the same way. If scratch disks are constantly being hit, the OP would likely benefit from more from ram than they would from something like an ssd. One is faster than the other, and a photographer isn't likely to fit all of their work onto ssds given the cost per GB. We need more information to make any kind of determination here, but 8GB would be the minimum I'd suggest as it is Adobe's recommendation in their system requirements.

Blah I forgot to mention earlier, if you upgrade the ram, test every stick prior to placing that machine back in service. If that means the ram sits on your desk for a few days, so be it. I don't care where you purchase it. Upgrades must be tested.

8GB is on the edge. If you're using Lightroom or Aperture you will want a tad more memory. I would suggest instead of going directly to 32GB consider buying a 16GB memory kit to go in to the empty slots. 24GB will be more than enough.

RAM is cheap, so you might as well go for 16gb.

If you use the "Free Memory" app for your iMac, you can keep an eye on your usage and free it up when needed. Later on you can upgrade your RAM, PS should work ok with 8GB. I'm on last years 27" iMac and have no problems. You could always just grab one 8GB stick and then you'd have 12GB, paired with one of your current 4GB sticks.

scottgoh said:

The scratch disc is my 1TB Fusion drive.

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That might be fine, especially if you disable spotlight searching on the system folders where the scratch disk page files are dumped. It comes down to if you're getting sufficient performance. Obviously I don't know how much data is being written, but in my experience 8GB of ram won't hold everything in ram. It only matters if it's slowing you down. With the fusion drive, if it's using the ssd portion, you might not notice it, but 8GB really is the bare minimum in my mind for a new machine tasked with this kind of work. Prior to CS5 it was a little different. When photoshop was a 32 bit program, you had to rely on scratch disks no matter what. Keep in mind you are still affected by drive speeds loading and saving files. Even if the drive is fast, files with any kind of compression (default on 16 bpc with layers) take a bit longer. Figuring out how to really improve performance always involves some amount of tracking down bottlenecks to ensure that you're addressing the right thing.

ijohn.8.80 said:

If you use the "Free Memory" app for your iMac, you can keep an eye on your usage and free it up when needed. Later on you can upgrade your RAM, PS should work ok with 8GB. I'm on last years 27" iMac and have no problems. You could always just grab one 8GB stick and then you'd have 12GB, paired with one of your current 4GB sticks.

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That would be a real waste since the 27" iMac has 4 memory slots.

You would want to add memory in pairs for best performance anyway. So either an 8GB or 16GB kit would need to be added and at the current memory prices, buying one 16GB kit is the best option.

Bear said:

That would be a real waste since the 27" iMac has 4 memory slots.

You would want to add memory in pairs for best performance anyway. So either an 8GB or 16GB kit would need to be added and at the current memory prices, buying one 16GB kit is the best option.

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Oh well, I stand corrected.

I was speaking from what I had to do with my old 21", maybe I should have been more specific there, sorry for that.

Bear, could you do a basic explanation of why it's necessary to add the RAM in pairs? I had no problems with my old iMac adding an extra 8GB stick to a 4 GB stick. It still has this setup and ticks along fine for the wife.

ijohn.8.80 said:

Bear, could you do a basic explanation of why it's necessary to add the RAM in pairs? I had no problems with my old iMac adding an extra 8GB stick to a 4 GB stick. It still has this setup and ticks along fine for the wife.

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If a pair of sticks are installed in a dual-channel capable system, the system can access both sticks simultaneously, essentially doubling the bandwidth to the memory. You might see a 5-10% performance increase for the system, vs having the same memory in a single stick.

A lot of systems had stability issues if the sticks weren't matched, thus the habit of selling them in pairs.

scottgoh said:

However, currently, OWC 32GB RAM is about US200+ and I feel that i can live without the upgrade until the price has dropped.

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I just at this, having paid $1k for 3MB of static RAM to go into my MacPortable back in the day.....

Welcome to Mac's and MacOSX.

mtbdudex said:

I just at this, having paid $1k for 3MB of static RAM to go into my MacPortable back in the day.....

Welcome to Mac's and MacOSX.

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Haha makes you just wonder how far we've come with our technology.