If you still need OS X El Capitan, use this App Store link: Get El Capitan. To download it, your Mac must be using macOS High Sierra or earlier. To download it, your Mac must be using macOS High Sierra or earlier.
I'm running El Cap on a late 2015 5k imac with 4GHz i7, 16GB RAM, and AMD Radeon R9 M395X with 4096MB. Basically 16GB of RAM away from being the top dog maxed out imac you can buy.
What I need to know is will Sierra slow my machine down, or possibly even speed it up? I've usually updated the new OS almost immediately after release with little problems, the only one being was choppy graphics performance in Yosemite.
El Cap seems to be running very nicely indeed on this machine and I don't want to take a backwards step in terms of performance. Running Sierra on mine since GM. No problems with performance. Also running it on an upgraded mid 2010 Mac Pro since release. I did have issues with dual GPUs (GTX 970 + GT 120) in Safari, but that was fixed in the latest version.
![Capitan Capitan](/uploads/1/2/5/4/125486755/887219928.jpg)
Another Mac I have running Sierra is close to the minimum supported, a mid 2010 white MacBook. I didn't try El Capitan on this Mac, but with an SSD + 8 GB RAM Sierra performance is definitely acceptable. And before it died, I had it installed on my unsupported late 2008 MacBook Air. In terms of performance, the early betas were terrible.
But the release version was about the same as El Capitan, which is to say, not great due to the underpowered nature of the hardware and only 2 GB RAM. I'm running El Cap on a late 2015 5k imac with 4GHz i7, 16GB RAM, and AMD Radeon R9 M395X with 4096MB.
Basically 16GB of RAM away from being the top dog maxed out imac you can buy. What I need to know is will Sierra slow my machine down, or possibly even speed it up?
I've usually updated the new OS almost immediately after release with little problems, the only one being was choppy graphics performance in Yosemite. El Cap seems to be running very nicely indeed on this machine and I don't want to take a backwards step in terms of performance. I am still with my 2009 Mac Pro (spec as per my signature). Sierra is more smooth then El Capitan, less bug for me as well. On my own computer, 10.11 has USB 3.0 bug (unable to recognise my USB 3.0 hub, card reader), GPU bug (not 100% sure it's from GPU, keep working on this with Apple Engineer for few months, and but they believe it's the GPU driver's bug, but never confirmed and fix the issue), slow shut down bug (may take 5+ minutes to shut down). With Sierra, USB normal, GPU normal, shut down normal.
And I didn't do any fresh installation since 10.7. So, if there is any 'my own rubbish' in the system causing the 10.11 malfunction, all those rubbish should still on my machine now with Sierra. However, what I realise is that Sierra definitely use more memory than El Capitan. May be my 48GB RAM helps, therefore my Mac can works better in Sierra.