hoakley Macs, Technology

Should you buy a Mac with a T2 chip? Costs, benefits, and problems

Apple’s latest iMac models – the iMac Pro – and MacBook Pros now offer the T2 chip, at additional cost. Is that cost worth paying? What features does this chip currently bring, and why might you not want one?

Cost

Apple doesn’t currently offer any simple price comparisons, as there’s no otherwise identical variant which is available with and without the T2 chip alone; it comes packaged with other enhancements. The two most direct comparisons are given below, with current prices given in £, which are now roughly the same as $ and €.

For iMacs:

  • iMac with a 3.6-4.2 GHz 4-core i7, Radeon Pro 560 graphics, 32 GB memory, 2 Thunderbolt ports, and 1 TB SSD £2799
  • iMac Pro base configuration with a 3.2-4.2 GHz 8-core Xeon W processor, Pro Vega 56 graphics, 32 GB memory, 4 Thunderbolt ports, and 1 TB SSD £4899

Here, the cost difference is a massive £2100, which brings an extra four cores and more recent processor, improved graphics, two additional Thunderbolt ports, as well as the T2 chip.

For MacBook Pros:

  • MacBook Pro 13-inch with a 2.3-3.6 GHz 2-core i5 processor, Iris Plus 640 graphics, 8 GB memory, 2 Thunderbolt ports, and 256 GB SSD £1449
  • MacBook Pro 13-inch Touch Bar with a 2.3-3.8 GHz 4-core i5 processor, Iris Plus 655 graphics, 8 GB memory, 4 Thunderbolt ports, and 256 GB SSD £1749

The cost difference is a far more reasonable £300, which brings an extra two cores, improved graphics, two additional Thunderbolt ports, Touch Bar, and the T2 chip.

Benefits

The current benefits specific to the T2 chip are in improved security, the potential for better internal SSD performance, enhanced tone mapping in the FaceTime HD camera, and in the case of MacBook Pros, the Touch Bar.

The T2 chip integrates the System Management Controller (SMC), an image signal processor, an audio controller, an SSD controller, and a secure enclave processor. Although future versions of macOS will undoubtedly enable more features of the T2, perhaps including facial recognition, those currently available fall into three groups: security, storage, and image.

Security features include:

  • Encrypted storage. All internal SSD storage in Macs with T2 chips is encrypted, either using keys based on the T2 chip alone, or in conjunction with a key supplied as part of FileVault. As the latter appears to come at no performance cost, everyone using a Mac with a T2 chip should enable FileVault. There doesn’t appear to be an option to disable the default encryption performed by the T2.
  • Secure Boot. There are three levels provided, ranging from Full to None, and you can additionally disallow booting from external storage. These are configured in the Startup Security Utility, which is accessed from Recovery mode.

Storage management results in incremental improvement to internal SSD performance, even though this now includes encryption of the internal SSD. Laptop Mag has benchmarked a MacBook Pro using the same BlackMagic performance tests which I use here, and reported an average write speed of 2682 MBps, which compares with 1900 MBps which I obtained on a similar MacBook Pro without a T2.

Image processing is currently limited to enhanced tone mapping, improved exposure control, autoexposure, and white balance for the built-in FaceTime HD camera.

Problems

At present, the most serious issue with T2-equipped Macs is that they cannot boot from network volumes. If your Macs need to support network booting (NetBoot, NetInstall, or NetRestore), then they must not have T2 processors. Apple hasn’t, as yet, provided any workaround for this.

Any damage to the T2 chip could result in it being unable to decrypt the contents of internal SSDs. As a result, Apple stresses the importance of maintaining good external backups. You can’t, for example, simply pop the SSD out and access it from a drive enclosure using another computer (in any case, most of these SSDs are now soldered in too!). Because keys from the T2 chip are used in the encryption process, decryption can only occur when that exact same chip is able to perform the decryption (although some forensic tools may now be able to work around such encryption).

The combination of T2, FileVault, APFS, and soldering-in of SSDs is probably going to make recovery of data from an internal SSD practically impossible, for the forseeable future.

Conclusions

If you need a Mac to keep sensitive data secure, particularly when travelling with it, T2-equipped models appear to make excellent sense, and the premium in terms of cost need not be that great.

The iMac Pro sets out to be in a class of its own, and for pricing it clearly is. I expect Apple to release new iMacs, some including T2 chips, at more affordable prices in September. So unless you really want to pay that much for an iMac Pro, you might be wise to hang on another couple of months.