AMD Ryzen 7 5800X3D Not Overclockable, Report Claims

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Extra cache, but no extra clocks.

AMD's enthusiast-grade Ryzen 7 5800X3D processor with a massive 96MB L3 cache supports everything that the company's latest CPU series has to offer in an attempt to be the best CPU for gaming, but according to a post on Bilibili that also features the first known picture of the chip, the chip doesn't support overclocking. A recent video interview with AMD representatives also implies that this could be the case (below). 

As you can see above, the Bilibili poster claims the chip isn't overclockable, which makes plenty of sense. When AMD announced its Ryzen 7 5800X3D processor several months ago, it emphasized its gargantuan 96MB L3 cache and increased single-thread performance thanks to fast memory accesses, an important factor for games. However, AMD didn't emphasize overclocking capabilities or clock rates compared to the regular Ryzen 7 5800X model.

Apparently, to add cache, AMD had to sacrifice clock speeds and may have also cut overclocking support. Additionally, AMD's website doesn't list the chip as overclockable, while it does list other models, like the standard 5800X, as overclockable. 

TechPowerUp also claims that AMD is asking its motherboard partners to disable overclocking support for its Ryzen 7 5800X3D chip, as despite the X letter in its model number, it is not exactly overclocking friendly. 

There are technical reasons why AMD's Ryzen 7 5800X3D had to lower clocks and disable overclocking. First, AMD places its 3D V-Cache on top of Zen 3's 'native' L3 cache and then connects them using through silicon vias (TSVs). This creates a non-uniform surface of the die, complicating positioning the integrated heat spreader (IHS) on top of the chip. To make it even, AMD places structural silicon spacers on top of Zen 3's processing cores, which limits their ability to dissipate heat. Yes, silicon does serve as a good thermal conductor, but it still traps a non-zero amount of heat between the die, structural silicon, and IHS. 
 
Because a 64MB 3D V-Cache tile also adds to the power consumption, AMD had to lower the base clocks by 400 MHz to maintain a 105W default TDP. For the same reason, overclocking capabilities are likely also affected, so disabling overclocking support on X3D CPUs makes sense.
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