PS4 Pro 'boost mode' runs unpatched PS4 games more smoothly

UPDATE 3/2/17 8:45pm: Sony has confirmed boost mode and offered a statement about its capabilities. According to word received by The Verge, boost mode "lets PS4 Pro run at a higher GPU and CPU clock speed in order to improve gameplay on some PS4 games that were released before the launch of PS4 Pro. Games that have a variable frame rate may benefit from a higher frame rate, and load times may be shorter in some games too."

UPDATE 3/2/17 7:52pm: Since publishing this story, the 4.5 system software update has started to roll out in volume to beta testers, and we can fully confirm that boost mode is indeed a real feature coming to PlayStation 4 Pro users. Digital Foundry will be putting this feature through its paces as soon as possible. In the meantime, here's a look at the option as it appears on the English version of the firmware.

Original story: Sony has revealed new details for its new system software 4.5 update, including long-awaited support for external hard drives, but if reports online are to be believed, it seems that the new firmware also adds 'boost mode' support to PlayStation 4 Pro, allowing non-patched standard PS4 games to tap into the power of the new hardware.

The news comes via a screenshot we first saw on NeoGAF, reproduced below, which appears to originate from a Japanese version of the 4.5 beta. The relevant text, along with a translation provided by DF staffer John Linneman is below:

PS4 Pro (CUH-7000シリーズ)の発売より前にリリースされたゲームをプレイする前に、フレームレートの向上などによって、高品質なゲームプレイを楽しめる場合があります。ゲームプレイ中に期時しない動作が生じる場合にはオフにしてください

Translation: "In some cases it is possible to enjoy high-quality gameplay such as improved frame-rates with software released before the PS4 Pro (CUH-7000 series) went on sale. If you encounter any unexpected behaviour during gameplay please set this option to off."

On the face of it, it seems that Sony has taken onboard a suggestion we made all the way back in August for an option where Pro power could be deployed on all existing, unpatched PS4 software. As things stand, when a standard PS4 title runs on the Pro, the hardware downclocks CPU and memory bandwidth, dropping GPU frequency and deactivating half of the Pro's 36 compute units - in effect transforming the machine into the base model.

By opening up the Pro's additional CPU and GPU power, unpatched PlayStation 4 titles could potentially run more smoothly. Games that aim for 60fps but don't quite hit the target - for example, Tomb Raider Definitive Edition or Project Cars - stand a better chance of sustaining a locked 60fps. Similarly, games with a 30fps target that are subject to noticeable frame-rate drops - like Batman: Arkham Knight, Just Cause 3 and The Witcher 3 - could also stand to benefit. Titles using dynamic resolution scaling, including Doom 2016, could also see improvement from more sustained performance and a tighter lock on higher resolutions.

However, to be clear, what we won't see will be games running at frame-rates higher than their established caps, and neither will we see drastic changes in resolution. Games that do consistently hit their performance targets will look and play exactly as they do already.

Another aspect to potentially consider is how Sony has implemented this feature and to what extent the Pro's capabilities are unlocked for base PS4 software. When we met PS4 system architect Mark Cerny and asked him about running base PS4 titles with Pro power, he stressed that compatibility with the existing range of 700 titles was of primary importance. Right now, we don't know whether full Pro capabilities will be deployed on base titles - if compatibility is problematic, Sony may take another route. For example, it may choose to boost GPU clocks to the Pro standard 911MHz, but leave the rest of the base mode running at standard spec. Assuming the feature is indeed included in the new 4.5 firmware, hopefully more details will emerge soon.

As things stand, the reports are exciting but remain unconfirmed and we've contacted Sony to ask for confirmation. We'll update when we have more news.