I can’t give you exact numbers on thermals for the newest iMac revision, only general guidance based on my own experience. There should be a few sites online that have that info if you go digging, though — just make sure you’re looking at the newest revision with the config you’re interested in, as supposedly cooling is a bit better for this generation compared to the last.
The main downsides to hackintoshing are:
- Component compatibility
- Initial setup
- Maintenance and updates
For the first, most Intel CPUs + motherboards work fine. AMD CPUs + mobos technically work, but with a big asterisk… because real Macs are Intel only, you have to trick macOS into thinking it’s running on a circa-2011 Intel CPU for it to work, but this causes some things to break because the CPU is missing features that the OS/apps are expecting to be there (for example Docker and VMWare, which need VT-d).
Nvidia cards don’t work under macOS at all unless you’re willing to use an old version of macOS, because Apple wants access to driver source code so it can apply its own optimizations to GPU drivers, but Nvidia is incredibly secretive and wants total control. So if your tower has an Nvidia GPU, you’ll need to swap that out for an equivalent AMD card, unless you’re OK with not having much graphics horsepower under macOS, in which case you can switch the Nvidia card off and use integrated graphics when booted into macOS.
Wifi compatibility can also be a challenge. By default, macOS supports the Atheros and Broadcom chips that Apple ships in real Macs, but not the Intel wifi that a lot of motherboards come with. The community is developing its own Intel wifi drivers, but they’re still very much beta quality.
Initial setup varies depending on your hardware. There’s a general process that works most of the time, but each system has its own unique quirks that you’ll have to fix or work around. It can range from being as easy as installing Linux (pretty easy) all the way to quite involved.
Maintenance/updates can be a challenge, once again depending on your hardware. Generally the easier the machine was to get up and running with macOS, the more pain-free updates will be. The more third party drivers, etc you need to use, the more likely it is that something will break when you update. Because of this, it’s standard practice to snapshot the system before updating so you can roll back if something breaks.
All that aside, they’re quite stable and are as good or better than a real Mac. It’s definitely more suited for someone with a tinkerer’s mindset, though… not at all your set it and forget it experience of a real Mac or Windows.
The benefits of higher RAM speeds aren’t particularly visible for most tasks people buy iMacs for, even on the high end. Even the Mac Pro, which is a true workstation machine (top end config uses a 28 core 64 thread Xeon), tops out at 2933Mhz RAM. Intel CPUs also aren’t all that sensitive to RAM speeds (contrasted to Ryzen, where it’s critical).
Thankfully, RAM is user upgradable in the 27" iMac and Mac Pro, so there’s no reason you have to buy your RAM from Apple. It’s pretty standard practice to configure the minimum and upgrade it with your own aftermarket RAM.
