Cus­tomised PC

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

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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

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