Homy, on 09 January 2020 - 07:49 PM, said:
Now that AMD has announced that Radeon RX 5600M and 5700M
will be coming later this year I'm sure we'll see an iMac update too this year instead of 2021. Until now AMD hasn't had any suitable GPUs for iMac after Radeon Pro 555-580 from 2017. I also think that the reason AMD didn't announce a launch date may be that Apple wants to have the GPUs in the new iMacs first, like they did with MacBook Pro 16". Apple is now officially AMD's partner and was mentioned and had its logotype at the AMD presentation during CES (for the first time I think).
Apple may use Radeon Pro 5600M and Pro 5700M like Pro 5300/5500M in MacBook Pro instead of RX M. These GPUs have more compute units but lower clock speed than RX. The 21.5" iMacs will have 5300/5500 and the 27" iMacs will get 5600-5700. On the other hand since these GPUs are already mobile ones with lower power consumption the iMacs may get the RX GPUs instead of the downclocked Pros in MacBook Pro.
It's been only 2,5 years since Apple began to use desktop GPUs in iMac 2017, but it doesn't mean they can't or won't use mobile GPUs anymore. Unless they redesign iMac there are not so many options for GPUs this year. The current Radeon Pro 580X uses 150 W so the new cards must have similar power usage or they'll be too hot for iMac. RX 5500 XT, 5600 and 5600 XT use 130-150 W so they would fit but 5700 and 5700 XT use 180-235 W so I think they are out of question, not to mention 5800 and 5900 people speculate about.
Apple also usually uses better GPUs in 27" so if they go for desktop GPUs they only have 5500-5600 to play with. They also always have an option for a top GPU like Vega 48 in current iMac 27".
So if they can't use 5700 and 5700 XT as a top GPU the 5600 XT must become the top choice for build to order. Then they may use 5500 XT, 5550 XT and 5600 in iMac 27" like the old 570X, 575X and 580X.
Then they have to use something like 5300 XT and 5350 XT that currently don't exit for iMac 21.5". They probably could also nerf RX 5700 by 30 W and have it as a top GPU but then they'll have to nerf 5600 XT to justify the option.
In the end it's all a game of speculations but with these new desktop and mobile GPUs I'm pretty sure we'll see new iMacs this year instead of 2021.