Case mods, tools, techniques, water-cooling gear and everything to do with PC modding Threadripper compatibility isn’t enough – CPU coolers need much larger contact plates
I’ve been playing with AMD’s Threadripper CPUs for most of August and I was also lucky enough to head over to LA to the launch as well. It’s great to see such interest in the PC, and the new X399 platform even looks more exciting than Intel’s X299 equivalent, with more I/O options and, of course, those huge CPUs and TR4 sockets.
With 16-core CPUs costing just £999 inc VAT – the same price as Intel’s 10-core Core i9-7900X, there’s plenty of scope for building a massively multi-threaded rig to blitz through video encoding and rendering tasks for a much lower price than an equivalent Intel system. Having focused on Threadripper CPUs this month, standard AM4 and LGA1151 CPUs suddenly look physically very small too.
For a while now, there have only been three basics socket types for cooler manufacturers to support – Intel’s LGA115x and LGA2011 sockets, plus variations of AMD’s CPU socket, which had similar mounts across various FMx and AMx sockets. Intel’s Skylake-X CPUs aren’t physically much different to their predecessors, as they have similarly sized heatspreaders and identical CPU sockets too. Basically, cooler manufacturers haven’t really had to change their plate designs much over several CPU generations, as both the heatspreader size and socket design have stayed pretty much the same. However, Threadripper is an entirely different proposition.
Firstly, we’re dealing with an entirely new CPU socket – TR4. It has a similar mounting method to LGA2011-v3, with four threaded holes allowing coolers to secure directly to the CPU socket with no need for backplates or plastic mounts as with LGA1151 or Socket AM4. However, the threaded holes are in completely different locations to LGA2011-v3, so Threadripper will require a complete redesign of some coolers at worst, while some may technically get away with adaptors for current coolers.
The real issue, though, is that AMD has essentially combined two quadcore Ryzen dies to make Threadripper,
Standard AM4 and LGA1151 CPUs suddenly look very small compared with AMD’s new TR4 processors
linked by infinity fabric, and the resulting CPU is even bigger than a two-die Ryzen chip. In order to space out the two dies to reduce the heat concentration, and possibly to save costs, AMD decided to create a CPU that was the same size as its EPYC server CPUs, but without two of the four dies. Underneath the heatspreader, AMD EPYC 32-core CPUs and Threadripper 16-core CPUs look identical, with four dies.
However, two of the four dies are essentially dummies on Threadripper CPUs and are only there to support the heatspreader. A Threadripper CPU is considerably larger than a Skylake-X CPU. So much so, in fact, that anyone wishing to own one has a bit of a problem. The heatspreader surface area is so massive that no current coolers can cover all of it. Critically, many smaller heatsinks and even some all-in-one liquid coolers not only fail to cover the entire heatspreader, but some of them can’t even cover both the active cores.
The two active dies are arranged diagonally, which makes sense from a cooling point of view. However, this setup also means the entire length of the heatspreader ideally needs to be sitting underneath the contact plate of your cooler. The heatspreader will allow the heat to be spread over a larger area, but it’s still important for any heatsink to cover the main hotspots – in this case, the two dies on a Threadripper CPU.
Unfortunately, practically every CPU cooler available at the moment has a contact plate that’s simply too small. Most heatsinks are only designed to deal with a CPU surface area no bigger than Intel’s high-end desktop, CPUs such as Skylake-X, with heatspreader dimensions of around 39 x 39mm. The heatspreaders on Threadripper CPUs, on the other hand, stretch to 68 x 51mm. What’s more, they’re rectangular, rather than square. Even the latest waterblocks, which usually have larger contact plates than heatsinks and all-in-one liquid coolers, still fail to encompass the whole heatspreader of a Threadripper CPU.
AMD includes an adaptor with TR4 CPUs, which is compatible with Asetek-made all-in-on liquid coolers, such as NZXT’s Kraken series. However, as you can see above, even with a generous amount of thermal paste across the entire contact plate, a huge amount of heatspreader is still left to fend for itself.
From photos I’ve seen of naked Threadripper CPUs without their heatspreaders, it looks likely that small portions of the dies won’t be fully covered by the contact plates on most all-in-one liquid coolers. Or, at the very best, the area of heatspreader just outside the dies will be left to fend for itself.
Thankfully, there are already some proper Threadripper cooling options. Noctua has announced Threadripperspecific coolers in the form of the NH-U14S TR4-SP3, NH-U12S TR4SP3 and NH-U9 TR4-SP3. These coolers have enlarged contact plates that deal with the huge heatspreaders on Threadripper CPUs. You can clearly see the difference between one of these coolers and one of its smaller contact plates on a standard cooler in the below snapshot of a video from SweClockers’ YouTube channel. The coolers aren’t compatible with other sockets and similarly, Noctua has apparently said it will not be retrofitting its past coolers with TR4 compatibility nor offering adaptor kits.
Water cooling is another option, as many waterblocks already have contact plates that are larger than those of all-in-one liquid coolers or their air-cooled siblings. I’ve spoken to EK Water Blocks, for example, which says it’s working on a Threadripperspecific waterblock that will presumably be much larger than its other blocks.
It will be interesting to see how the first batch of coolers that claim to support Threadripper will fare with these monster CPUs, but it’s my guess that they’ll struggle, or at the very least, will see certain cores reaching much higher temperatures than others. I’ll hopefully be taking a look at these offerings soon to see how they cope with AMD’s new desktop CPUs, and to see if they offer any benefits compared with standard coolers sporting tweaked mounting kits. You can also see AMD’s list of coolers that officially support Socket TR4 at
Above left: AMD includes an adaptor that’s compatible with Asetek-made allin-on liquid coolers, such as NZXT’s Kraken series Above right: Even with thermal paste spread across the entire contact plate, a huge amount of heatspreader is still uncovered Noctua’s Threadripper contact plate next to its standard plate Image credit: SweClockers’ YouTube channel