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macOS Big Sur FAQ: All your questions answered

Apple's promotional image for the macOS Big Sur software update for Mac computers

Some people have already downloaded, installed, and gotten used to macOS Big Sur. The newness has probably already worn off for them! But if you’re still contemplating whether or not you should, aren’t sure if you’re Mac model can handle it, or just want some basic questions answered, here’s your macOS Big Sur FAQ.

Upgrading to iPhone Xs via Apple’s Upgrade Program? Here is what you need to know

This will be my first year upgrading to the new iPhone as a member of Apple's iPhone Upgrade Program. Say what you want about the poor economics of the 'leasing' model, but with no need to list my old phone on eBay or fork over $1,000+, this may be one of my most stress-free iPhone upgrades ever. That being said, there are a few things worth noting if you're planning to upgrade to the new iPhone Xs or Xs Max using Apple's Upgrade Program. 

Last chance to downgrade iOS and tvOS, and save blobs for a jailbreak!

Update: tvOS 11.1 and iOS 11.1.2 are now unsigned.

DO NOT ATTEMPT TO RESTORE TO THEM!

New exploits for iOS 11.1.2  and below have made the possibility of upcoming jailbreaks very real. However, without the proper preparation, you could be left in the cold, without blobs to restore, or on the wrong firmware. Also, not everyone should update, so you need to be sure it's for you. Let's go through the options.

iFixit’s $300 kit lets you boost the RAM on Apple’s new 21.5-inch iMac to 32GB

Repair experts at iFixit have announced a DIY $300 upgrade kit for the new 21.5-inch iMac with 4K Retina display after finding user-replaceable RAM via a pair of removable SO-DIMM slots instead of the memory modules being soldered onto the logic board.

The baseline 3.0GHZ Core i5 machine has 8GB of RAM, which can be maxed out to 16GB.

Customers who need more RAM can opt to double the machine's 8GB of RAM to 16GB of RAM for an additional $200 via Apple's build-to-order options. However, only the $200 pricier system with Intel's 3.4GHz Core i5 chip allows you to boost the RAM all the way up to 32GB but the build-to-order option adds a whopping $600 on top of the price of that system.

Therefore, it makes a lot of sense from a financial standpoint to invest into a third-party DIY kit if all you need is more RAM, up to 32GB, on the baseline model.

The iMac Intel 21.5" Mid 2017 Max RAM Upgrade Kit includes the following:

Two 32GB (2x16GB) DDR4-PC2400 2400MHz RAM modules Replacement Display Adhesive Strips iMac Opening Wheel iMac Service Wedge Plastic Cards Spudger Tweezers Phillips #00, T5, T8 and T10 Bits Driver Handle

iFixit's repair guide details the 63 steps required to replace the RAM.

Although the machine features removable RAM sockets, the RAM is not meant to be user-replaceable because getting to the memory modules requires removing the back cover, the display, the logic board and other components.

In other words, the procedure isn't for the faint-hearted.

Opening them machine involves cutting through adhesive that will need to be reapplied after you finish the repair. You'll also need to remove the logic to remove or replace the RAM.

From the iFixit team:

This guide is marked "potentially dangerous" because it requires you to handle a power supply that contains large capacitors. Unplug the iMac and hold the power button down for at least 10 seconds to help discharge the capacitors. Handle the board by the edges and do not touch surface components.

iFixit also noted that the machine's Kaby Lake processor sits in a standard LGA 1151 CPU socket rather than being soldered onto the logic board. “For the first time in years it's possible to replace or upgrade the CPU without a reflow station, and that's a big win,” wrote iFixit.

Considering that the baseline iMac provides options for 8GB or 16GB of RAM, but not 32GB, this is currently the only way to bring the machine up to the higher capacity.

Last chance to save blobs for, or restore to, iOS 10.3.1

The signing window for iOS 10.3.1 could close any moment now, with iOS 10.3.2 released and iOS 10.3.3 in beta already, so this is your last chance to save your blobs for iOS 10.3.1, to upgrade to it from a lower firmware, or to downgrade to it from iOS 10.3.2+.

iOS 10.3.1 isn't currently jailbroken, and being on that firmware is in no way a guarantee of a jailbreak. However, you never know what'll happen, and there have been some stirrings, so act now! Take necessary precautions before signing ends.

How to restore your device to iOS 9.x with iDeviceReRestore

A while back we broke the story of a bug which was allowing restores to iOS 9 firmwares, without even needing a jailbreak. It was subsequently discovered that the bug was more far-reaching than originally thought, allowing restores to iOS 9.x from any firmware, not just from iOS 9.

The tool was released a week or so ago, and so we thought the time was right for a tutorial. Follow our instructions here to bring any 32-bit device back to any iOS 9.x firmware you have blobs for, from any starting firmware. No keys, bundles, nonces, or jailbreak required!

iOS 9.x Re-restore bug even more powerful than previously thought

I reported a few weeks back on an interesting new bug for 32-bit devices, which allowed you to restore them to any unsigned iOS 9.x firmware, provided you had blobs for the destination firmware.

At the time, it was thought that the bug would mainly be of use for people downgrading from iOS 9.3.5 to a lower firmware, to jailbreak with Home Depot or Pangu9. However, it turns out the bug is in fact more powerful and wide-ranging than previously thought, and may have much wider utility.