Apple has already announced that there will be new iMacs released later this year, but rumours are now circulating that towards the end of 2017 Apple will also release an iMac with ‘server-grade’ components and the upgrades to the existing iMacs Now expected in September 2017.

What Do We Know Already?

Regarding iMacs, Apple marketing chief Phil Schiller said in the briefing to some hand-picked journalists that new iMacs are in the works,  for release sometime this year, including...

...configurations of iMac specifically with the pro customer in mind and acknowledging that our most popular desktop with pros is an iMac.

Craig Federighi who is Apple's senior vice president of Software Engineering added...

That is a pretty incredible evolution that we’ve seen over the last decade. The original iMac, you never would’ve thought as remotely touching pro uses. And now you look at today’s 5K iMac, top configs, it’s incredibly powerful, and a huge fraction of what would’ve traditionally — whether it’s audio editing, video editing, graphics, arts and so forth — that would’ve previously absolutely required the Mac Pros of old, are being well-addressed by iMac. But there’s still even further we can take iMac as a high performance, pro system, and we think that form factor can address even more of the pro market.

What Does Server Grade Mean?

A number of Mac rumour sites are quoting an article from Digitimes that... 

...according to sources from Taiwan-based supply chain makers, Apple is also testing a new server-grade iMac for the high-end sector. The new server-grade iMac is expected to feature Intel's Xeon E3-1285 v6 processor, 16-64GB ECC RAM, up to 2TB NVMe SSD and a latest discrete graphics card. The product is unlikely to become available in the market until the end of 2017.

Pike's Universum is quoting an unnamed source that backs up the Digitimes sources by saying...

Intel E3-1285 v6 processor with 16 GB (upgradable to 32 or 64 GB) ECC memory. Faster NVMe SSD’s possibly up to 2 TB and AMD graphics to support VR and Pro apps.

But they go on to add that the new iMac Pro will have Thunderbolt 3 and USB-C gen 2 and will come with a brand new keyboard.

• Xeon E3-1285 v6 processor - This is a brand new yet-to-be-released processor from Intel which would bring Apple back up to date on the processors in Macs.

• ECC RAM - This automatically protects against data corruption in the memory, increasing the reliability of the overall system. ECC stands for error correcting code memory and is designed to protect memory from single-bit memory errors which apparently can be caused by cosmic rays. However, it is more likely that radioactive decay and electrical interference would be the cause single-bit memory errors, which are problematic for users who handle highly sensitive data — like financial records, or scientific data.

• Latest discrete graphics card - Typically, current iMacs include a mobile-class GPU rather than a desktop-class card, so this could refer to the AMD contract with Apple to supply the discrete graphics chips for future high-end 27-inch iMacs.

Other New iMac Upgrades Coming Sooner?

The Digitimes article also suggests that there will be upgrades to the current 21.5-inch and a 27-inch iMacs expected to be released in the third quarter of 2017 "to catch up with the year-end holiday season".