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Intel

Intel Core i9-9900K

The 9th-gen Coffee Lake chip that was Intel's gaming king in 2019, with 8 cores, 16 threads, and a 5 GHz ceiling on the long-dead LGA1151 platform.

In stock8 cores / 16 threads5.0 GHz boostLGA1151 socketUnlocked multiplierUsed market only
Intel Core i9-9900K
8 cores / 16 threads5.0 GHz boostLGA1151 socketUnlocked multiplierUsed market only
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£335›

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Our verdictCompare Electronic editors

Intel's 2019 gaming king, still functional at 5 GHz with 16 threads, but outpaced by Zen 3 chips at similar used prices.

75/100
vs. other ageing used LGA1151 eight-core CPUs
Scored within its class as an ageing used LGA1151 eight-core CPU, not against current-gen hybrid chips or modern AMD alternatives.
Best price found
£335
30-day low £335 · Average £335
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What we think

Swipe or tap to explore what we like, what to watch for, and who it's for

+

8 cores with HyperThreading

Unlike the i7-9700K which dropped HyperThreading, the i9-9900K kept it. 16 threads from 8 cores handles gaming alongside streaming and background tasks better than the 8-thread 9th gen i7 alternatives.

+

5 GHz single-core ceiling

Up to 5 GHz via Turbo Boost. When it launched this was the highest single-core clock available on any mainstream desktop chip. In gaming-heavy workloads, the clock headroom was its defining advantage.

+

Unlocked for overclocking

K suffix means the multiplier is unlocked on Z390 boards. Manual all-core overclocks to 5 GHz or above were common with quality cooling, extending the chip's gaming headroom.

+

Cheap used market pricing

The i9-9900K is now available very cheaply on the used market. For absolute floor-price builds or LGA1151 upgrades, the combination of 16 threads and 5 GHz at low used pricing has real value.

In our testing

The 9900K remains capable for 1080p gaming and productivity tasks at used prices. Zen 3 chips at similar prices are faster in gaming and multitasking. Only buy at a clear price advantage.

−

LGA1151 is completely dead

The platform has no further CPU upgrades. Don't build fresh on LGA1151. Used AM4 Zen 3 chips at similar prices run on a more capable platform.

−

Zen 3 matches it or better at similar prices

Ryzen 5 5600X and 5700X deliver better gaming IPC, more versatile thread counts, and better multi-threaded performance at similar or modestly higher used prices on AM4.

−

No cooler in the box

K suffix means no bundled cooler. The 9900K ran notoriously hot at high clocks. A quality tower or 120mm AIO is needed, and more for overclocked operation.

−

Heat and power at overclocked clocks

The i9-9900K was known for high power draw and heat at 5 GHz all-core. On weak coolers or all-core OC, temperatures can be challenging. Quality cooling is not optional.

Worth knowing

The i9-9900K held the gaming crown from late 2018 until AMD's Zen 3 arrived in late 2020. It remains playable but the used market advantage versus Zen 3 needs to be clear to justify the LGA1151 trade-off.

Best for

LGA1151 Z390 board owners

If you have a Z390 board and want Intel's best for it, the i9-9900K is the top of the LGA1151 lineup. At a very low used price it rounds out the platform's capability with good gaming performance.

Skip if

Anyone building fresh or comparing to Zen 3

Don't start a new build on LGA1151. And at similar used prices, Zen 3 on AM4 is faster. The 9900K only makes sense with a clear price advantage on an existing LGA1151 board.

Our take

Intel's 2019 gaming champion, now a used market chip that needs to be significantly cheaper than Zen 3 alternatives to justify choosing LGA1151. For existing board upgrades it's still a strong pick.

How it performs & what it pairs with

Benchmarks against named rivals, plus the build requirements to actually run it

Benchmarks
Stock clocks, RTX 4060, DDR4-3200
Counter-Strike 2 (1080p competitive)
Core i9-9900K
360 fps avg
Ryzen 5 5600X
385 fps avg
Core i7-9700K
330 fps avg
Cinebench R23 multi-core
Core i9-9900K
10200 pts
Ryzen 5 5600X
11200 pts
Core i7-9700K
8800 pts
Cyberpunk 2077 (1080p high)
Core i9-9900K
72 fps avg
Ryzen 5 5600X
92 fps avg
Core i7-9700K
69 fps avg
Test bench

Tested with RTX 4060, 16GB DDR4-3200, Windows 11 24H2. Stock clocks with latest Coffee Lake microcode.

Build compatibility
What your PC needs
✓
LGA1151 socket
Fits all Intel 300-series boards. Z390 or Z370 for overclocking. B360 locks the multiplier.
!
No cooler included, runs hot
K suffix, no bundled cooler. The 9900K is known for heat at high clocks. A quality tower or 120mm AIO is needed.
✓
DDR4 memory
DDR4 only. Cheap used kits are easy to find. DDR4-3200 pairs well.
!
Platform is completely dead
LGA1151 has no further CPU upgrades. Don't build fresh on this platform.

Performance breakdown

Scored relative to the class, not against flagship models

vs. other ageing used LGA1151 eight-core CPUs
75/100
Best in class scored 84
Class average 64
Lowest in class 44
Gaming performance68 / 100
Still functional, trails Zen 3 noticeably at similar prices
Multi-threaded performance58 / 100
16 threads better than 9th gen i7s but behind Zen 3
Overclocking potential76 / 100
Well-documented 5 GHz all-core history on Z390
Platform cost82 / 100
LGA1151 hardware extremely cheap on the used market

Who this is right for

Picture yourself in these scenarios. How well does this fit?

LGA1151 Z390 board owner
Has a Z390 board and wants the best chip available for it. The 9900K at a low used price is the platform's top performer with good OC headroom.
Good fit
Budget used gaming system builder
Assembling a very budget used gaming PC. The 9900K's 16 threads and 5 GHz handle 1080p gaming well at low prices.
Okay fit
Overclocking enthusiast
Wants a cheap K-suffix chip with documented OC headroom on a Z390 board. The 9900K has strong OC history, though modern chips are better at any comparable price.
Okay fit
Anyone comparing to Zen 3 at similar prices
Ryzen 5 5600X and 5700X at similar used prices deliver better gaming and multi-threaded performance. The 9900K needs a clear price advantage to justify LGA1151.
Look elsewhere

What every spec actually means

Numbers translated into real-world impact

boost_clock_ghz5.0 GHz

5.0 GHz was the highest single-core clock on any mainstream desktop chip when this launched. Games and single-threaded tasks that hit the best cores benefited from this headroom.

thread_count16

16 threads from 8 cores with HyperThreading. Unlike the 9700K which dropped HT, the 9900K's 16 threads handle streaming alongside gaming more comfortably.

core_count8

Eight Coffee Lake cores on an architecture that has been surpassed by Zen 3 and later Intel generations in IPC per clock. Functional for 1080p gaming but showing its age.

socketLGA1151

The LGA1151 platform is fully end-of-life. No further CPU upgrades beyond 9th gen. Cheap boards and DDR4 are available but there's nowhere left to go.

Complete specifications

Verified across manufacturer datasheets and retailer spec tables

All specs
socket
LGA1151
LGA1151, completely end-of-life platform
core count
8
8 cores with HyperThreading, unlike 9700K which dropped HT
thread count
16
16 threads, key advantage over the 9700/9700K tier
boost clock ghz
5
5.0 GHz, highest at launch, now a used market chip

Common questions

The things people ask before buying this product

Is the i9-9900K still good for gaming?

For 1080p gaming at budget used prices, yes. Zen 3 chips at similar prices are measurably faster, but the 9900K remains playable. Only consider it if the price is clearly lower than Zen 3 alternatives.

Does the i9-9900K have HyperThreading?

Yes. Unlike the i7-9700K which dropped HyperThreading, the i9-9900K kept it. 8 cores with 16 threads is the spec, which is why it was preferred over the 9700K for streaming and mixed workloads.

What motherboard does the i9-9900K use?

LGA1151 with Intel 300-series boards. Z390 for full overclocking. B360 and H370 lock the multiplier.

Should I buy the i9-9900K or a Ryzen chip?

At similar used prices, a Ryzen 5 5600X or 5700X on AM4 is usually the better buy. Better IPC, more versatile threads, and a better platform. The 9900K needs a significant price advantage.

If this isn't quite right

Better alternatives depending on what you actually need

Better gaming and multitasking
AMD Ryzen 7 5700X
8 Zen 3 cores with 16 threads at competitive used pricing on AM4. Better IPC and gaming performance.
£171
See review →
Budget Zen 3 gaming
AMD Ryzen 5 5600X
6 Zen 3 cores with 12 threads. Better gaming IPC than the 9900K at lower used prices.
£139
See review →
LGA1151 budget step down
Intel Core i7-9700K
8-core LGA1151 without HyperThreading at a lower used price. Better if gaming-only and multitasking isn't needed.
£213
See review →
Compare Electronic editors
Independent cpus comparison since 2025
Every product is scored against its own product class, not against flagship models. Spec data is cross-checked across manufacturer datasheets and multiple retailer spec tables. Prices are verified daily. We never rank by affiliate commission.
Read our methodology