It appears that Apple has solved a multi-GPU issue that has plagued AMD and Nvidia for years with the UltraFusion interface unveiled earlier this week, which allows two M1 Max chips to be connected together to create a single M1 Ultra chip.
When Apple announced the M1 Max last year, it didn't wisely reveal that there was a hidden secret embedded in the chip. This secret was revealed earlier this week at Apple's March event, where the company revealed that it could combine two M1 Max chips, making them one M1 Ultra with twice the power, including twice as many GPU cores.
Of course, Apple isn't the first company to harness the power of two GPUs. For many years, Nvidia graphics cards supported SLI (Scalable Link Interface), a high-speed link that allowed you to connect multiple GPUs at once to boost performance. AMD had a similar technology with CrossFire that did the same thing.
break the problem
The problem with SLI and CrossFire was that they weren't good enough to multiply the power of the PC by the number of installed GPUs. So if you had two Nvidia GPUs in SLI, you weren't getting twice the performance.
At best, the scenario would be a 90% improvement, but in many cases it's more like a 50% improvement, and that performance drops as you add more GPUs. The ROI just wasn't worth it for many people, especially if you paid for three GPUs, but instead skipped the power of 2.5 GPUs.
SLI and CrossFire also added overhead to the PC, especially with the CPU, which affected performance. Then there was also an increase in power consumption and thus running costs and cooling considerations, and the amount of space needed within a PC chassis and motherboard to accommodate multiple GPUs.
Finally, there was also an issue with apps, and games in particular, offering poor support, if any, for SLI and CrossFire. In some cases, a game would only use one GPU, regardless of how many are installed.
So it's perhaps no surprise that CrossFire and SLI have become extremely niche features, and AMD or Nvidia won't tell you about them. In fact, Nvidia basically did away with SLI a few years ago in favor of NVLink for their RTX cards. However, the price and the fact that it's quite difficult to try and buy an Nvidia GPU, let alone multiple GPUs, meant it wasn't appreciated.
However, with the M1 Ultra, Apple seems to have solved many of these problems. For starters, the UltraFusion connection was designed to offer extremely low latency (essentially a delay in data transfer, and the lower the better) between the two M1 Max chips, with a bandwidth of 2TB/s. . It's incredibly fast and much faster than SLI or CrossFire.
The speed of UltraFusion brings many benefits, the most obvious being performance, which is why Apple is confident that the M1 Ultra will deliver twice the performance of the M1 Max.
By turning two M1 Max chips into a single M1 Ultra chip, Apple has also avoided the performance overhead that multi-GPU setups often have. Although the M1 Ultra is now the largest chip Apple has ever made, it's still smaller than physical discrete graphics cards, allowing it to be used in the compact Mac Studio, which was also announced at Tuesday's launch event.
The M1 family of chips has also been acclaimed for its performance per watt, as it is much more energy efficient than competing chips. This allowed MacBooks with M1 chips to have longer battery life, while staying cool even when working hard, and the M1 Ultra continues that. According to Apple, the M1 Ultra's GPU offers better performance than Nvidia's powerful RTX 3090, while consuming 200W less.
It's certainly a bold statement, but in these times of rising energy costs, the energy efficiency of our components is going to be an important consideration. Rumors suggest that Nvidia's next-gen GPUs like the RTX 4080 will draw even more power, which could make Apple's approach that much more appealing.
Finally, Apple's approach also seems to be paying off when it comes to software support. Applications will see the M1 Ultra as a single chip, meaning no additional coding is required – it will be carrier ready to use, allowing applications to take advantage of the extra power. It's a key difference that could become a game changer.
Speaking of which, while Macs aren't traditionally thought of as gaming machines, games should also see the M1 Ultra as a single chip, allowing them to use the extra power. With the M1 Ultra seemingly beating the RTX 3090, could Apple have made a fantastic gaming GPU?
We'll have to wait to test Apple's claims for ourselves, but it certainly looks promising. Apple's victories here could also prompt Nvidia and AMD to reassess their multi-GPU technology, which could lead to increasingly impressive performance for gaming and professional use. We can not wait.
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