Intel BX80673I99900X

The i9-9900X posts a 21,553 PassMark multi-thread score, putting it in the top quarter of all CPUs we track. But the efficiency score of 55.1 and PCIe 3.0 platform hold it back hard. At $168 it's a steal for heavy productivity; at $500 it's a trap.

The multi-thread story is the one that matters. 21,553 in PassMark puts this chip ahead of most of our database, and in real terms that means video exports, code compiles, and 3D renders finish noticeably faster than on mainstream six or eight core parts. The 19.25MB of L3 cache helps keep those ten cores fed, and the unlocked multiplier means you can push past that 4.4GHz boost if your cooling can handle it.

Single-thread is where the age shows. 2,527 is solid but unremarkable, and the 3.5GHz base clock means lightly threaded workloads don't get the same love. If you're mostly gaming, you're leaving a lot of this chip's potential on the table. The quad-channel memory controller is a genuine perk for bandwidth-hungry work, but PCIe 3.0 means you're stuck with last-gen storage and GPU bandwidth.

Against the AMD Ryzen 7 9800X3D, the 9900X wins on raw core count but loses on basically everything else that matters today. The 9800X3D has modern PCIe, far better single-thread performance, and a fraction of the power draw. The 9900X does beat the older Xeon E5-2637 V2 and E5-2697 v2 in our database on multi-thread throughput, but those are ancient server pulls selling for pocket change. The G.Skill Trident Z Neo isn't even a CPU, so we'll skip that comparison. If you need cheap multi-thread grunt and find a 9900X under $200, it's interesting. Otherwise, a modern Ryzen or Core i5 will serve you better in nearly every scenario.

Value is where this chip gets complicated. The affordability score sits at 27th percentile, which is a polite way of saying this thing is expensive for what it delivers in 2025. US listings swing wildly from $168 to $500, and if you can find one at the low end, the math changes completely. At $168, you're getting top-quarter multi-thread performance for less than a mid-range modern CPU. At $500, you're paying a premium for an aging platform. European buyers face an even wider spread, from EUR 682 to EUR 942, and the best deal we see is at the bottom of that range. The real cost is the platform tax: X299 boards and quad-channel DDR4 kits add hundreds more to the total.

The Core i9-9900X posts a PassMark multi-thread score of 21,553, which lands it in the top quarter of all desktop CPUs we track. That's the headline here. Ten Skylake-X cores with 20 threads at a 4.4GHz boost will chew through renders and heavy multitasking without breaking a sweat. The single-thread score of 2,527 is less exciting, sitting just above average, so don't expect it to dominate in lightly threaded games or older apps.

But here's the thing. This chip launched into a world that has moved on. The efficiency score of 55.1 out of 100 is the weakest area by a wide margin, and that 165W TDP tells you why. You're paying for HEDT muscle on an aging 14nm process, and the platform costs add up fast. X299 motherboards aren't cheap, and neither is the quad-channel DDR4 this thing wants.

Skip this if you're building a new system from scratch. The efficiency score of 55.1 is the weakest area, and that 165W TDP means you'll need serious cooling and a quality power supply. Gamers should look elsewhere too, since the single-thread score of 2,527 won't push high refresh rates the way a modern chip will. If you don't already own an X299 board, the platform cost kills any value proposition. And if you're paying anywhere near the $500 or EUR 942 end of the price range, you're getting fleeced.

The i9-9900X is a niche buy in 2025. If you already own an X299 board and need more cores without a full platform swap, a used 9900X at the low end of the price range makes sense. The multi-thread score of 21,553 is genuinely strong, and for heavily threaded productivity it still delivers. But the efficiency score of 55.1, the PCIe 3.0 limitation, and the single-thread mediocrity mean this is not a chip we'd recommend for a new build. The platform is dead, the power draw is high, and modern mid-range CPUs beat it in most real-world tasks.