Since late 2018’s and early 2019’s 5G network launches are rapidly approaching, device makers are beginning to hint at the shapes of their initial 5G smartphones. Positioning itself as a rival to Qualcomm, Samsung, Huawei, and Intel, Taiwanese 5G chipmaker MediaTek has just shown off the latest version of its Helio M70 5G modem (via IT Home), notably inside a large prototype 5G phone that’s cooled with a fan.

As was the case with Qualcomm’s recently revealed “smartphone form factor” test device, MediaTek’s sample phone is atypically big since it’s designed for testing and tweaking, so one shouldn’t assume that final phones using Helio M70 will be as plasticky or oversized. According to IT Home, MediaTek staff at Taiwan’s IC60 Special Exhibition event are promising that “the final 5G commercial device will have MediaTek’s unique low-power design without fans.”

There’s every reason to believe that claim. No one wants to carry around a thick phone with a fan inside, even if Helio M70 will deliver its promised 5Gbps download speeds. It’s even possible that the prototype doesn’t use the small, more power-efficient 7-nanometer TSMC manufacturing process that MediaTek has slated for its final chip.

However, as a snapshot of where 5G chip development stands as of right now, the fact that a recent Helio M70 prototype requires a special cooling solution is significant. MediaTek was reportedly seeking Apple’s business for a 5G iPhone in July, and promising that its 5G modem would hit the market six months ahead of schedule. Because Apple has been locked in a highly public dispute with Qualcomm over modem chips for the past two years, and Intel is facing its own challenges with 5G engineering, Apple is said to be considering MediaTek modems as an alternative to Qualcomm and Intel parts.

It has been clear since early 2018 that early 5G devices will demand considerably more power than older 4G models, in part due to simultaneous 4G/5G connection requirements. The rush to get 5G into the marketplace has led to suspicions that Motorola, Samsung, and Huawei will launch 5G in larger and/or thicker devices with custom cooling solutions and bigger batteries. Though Qualcomm said last week that it was laser-focused on trying to keep device sizes down, competitor Huawei is apparently planning to include a large copper heatsink in its first 5G phone to dissipate the heat of its self-designed modem.

Regardless, Apple is expected to skip adding 5G to this year’s iPhones, and may do so again next year. If it does include 5G in a device next year, it might follow Samsung’s lead, offering it only as an option in its largest flagship phone. Depending on the progress of its engineering and demand, Apple could also debut the feature first in an iPad tablet rather than in a pocket-sized device.