AMD Ryzen 9 9900X review

With the retail launch of its Ryzen 9000-series of processors, AMD chose to stagger the releases, with the more affordable Ryzen 5 9600X and Ryzen 7 9700X hitting shelves last week. Now it's the turn of the top-end chips and first up is the $499 Ryzen 9 9900X.

Let me begin by confessing my bias for AMD's 12-core processors, as I really rate the Ryzen 9 7900X and 7900. The latter has been a solid workhorse of a chip, powering my primary AM5 test PC, running games and content creation apps with ease. Sure, the full-fat 16-core models top the charts when it comes to multithreaded performance and you can't beat the X3D chips, with their extra L3 cache, for gaming but the Ryzen 9 7900 really is a fantastic all-round CPU.

I was keen on seeing what the Zen 5 update of one of my favourite chips was going to be like but after reviewing the 9600X and 9700X, I realised that I would need to temper my expectations somewhat. What I didn't realise at the time was just how much I'd need to lower my hopes.

The Ryzen 9 9900X comprises three chiplets underneath the heatspreader—two CCDs (Core Complex Dies), each with six cores and 12 threads, and a single IOD (Input/Output Die). That's exactly the same as the previous Ryzen 9 7900X model but there are some further revisions, other than the obvious AMD Zen 5 architecture advances.

Cores: 12
Threads: 24
Base clock: 4.5 GHz
Boost clock: 5.6 GHz
L3 Cache: 64 MB
L2 Cache: 12 MB
Unlocked: Yes
Max PCIe lanes: 24
Graphics: Radeon Graphics
Memory support (up to): DDR5-5800
Processor Base Power (W): 120
Maximum Package Power (W): 162
Recommended customer price:  $499/£459.99

Where the 7900X has a base clock of 4.7 GHz and a TDP of 170 W, the new 9900X has a base clock of 4.4 GHz and a much lower TDP, just 120 W. The boost clocks are the same for both chips (5.6 GHz) so the new model has a smaller power budget with which to maintain boost clocks when under heavy load.

Upon installing the chip, the first thing I checked out was the idle behaviour, as this