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Buying Guide

The Best CPUs to Pair With an RTX 4090

From the Ryzen 5 7600X3D to the Ryzen 9 9950X3D: four processors ranked on L3 cache and boost clock, with who should skip each one.

By , PC Hardware Editor

11 min read4 products evaluated

PC components laid out on a workbench ready for a build
Illustrative image
Jump to
  1. Quick Picks
  2. Our Picks
  3. How We Chose
  4. What to Look For
  5. Comparison
  6. FAQ

An RTX 4090 is fast enough that the CPU often limits it below 4K. Every pick has 96MB or more of L3 cache or is Intel's top gaming chip, ordered by cache.

This is a research roundup, not a lab test: L3 cache, max boost and cores / threads come from each maker's published specs; nothing here was tested in-house, and gaps in the specs are flagged, not filled in.

Quick Picks

Which of the 4 picks to look at first. Tap a name for the full analysis.

  1. Also Consider

    AMD Ryzen 9 9900X3D

    3D V-Cache on a 12-core chip.

    Best for: Buyers who want 3D V-Cache on a 12-core chip.

    Check price for AMD Ryzen 9 9900X3D on Amazon (opens in a new tab)

  2. Premium Pick

    AMD Ryzen 9 9950X3D

    The top of this price range, adding 3D V-Cache on one of its two core dies.

    Best for: Spending more than the Ryzen 9 9900X3D costs for the fullest feature set in this group.

    Check price for AMD Ryzen 9 9950X3D on Amazon (opens in a new tab)

  3. Lowest Rated Power

    AMD Ryzen 5 7600X3D

    The lowest rated power here (65W).

    Best for: Buyers who put rated power first.

    Check price for AMD Ryzen 5 7600X3D on Amazon (opens in a new tab)

  4. Highest Boost Clock

    Intel Core i9-14900K

    The highest boost clock here (6GHz).

    Best for: Buyers who put boost clock first.

    Check price for Intel Core i9-14900K on Amazon (opens in a new tab)

Our Picks

Also Consider1 of 4

AMD Ryzen 9 9900X3D

The Ryzen 9 9900X3D adds 3D V-Cache to a twelve-core layout.

Best for

Buyers who want 3D V-Cache on a 12-core chip.

Skip if

Look at the others if this bothers you: no cooler in the box.
Check price on Amazon for AMD Ryzen 9 9900X3D (opens in a new tab)
AMD Ryzen 9 9900X3D

Why we like it

It sits between the eight-core X3D chips and the 9950X3D on core count and price. Its 5.5GHz boost clock ranks third of 4 here, behind the Core i9-14900K (6GHz) and ahead of the Ryzen 5 7600X3D (4.7GHz). On core count it sits mid-pack at 12 cores: the Core i9-14900K offers 24 cores, and the Ryzen 5 7600X3D comes in at 6 cores.

It needs an AM5 board (A620, B650, B850, X670 or X870 series) and DDR5 memory; a 600-series board may need a BIOS update first, so check the maker's CPU support list for the minimum version. Budget for a dual-tower air cooler or a 240mm-plus AIO, since none is included. It was priced above the Core i9-14900K and below the Ryzen 9 9950X3D at the time of writing.

Key specs

L3 cache
128MB
Max boost
5.5GHz
Cores / threads
12 cores
Rated power
120W
Threads
24
Socket
AM5
Memory
DDR5
Cooler in box
No
Integrated graphics
Yes

Pros

  • 128MB of L3 cache from 3D V-Cache
  • 5.5GHz maximum boost
  • 12 cores for encoding and background work
  • Integrated graphics for display output without a graphics card

Cons

  • No cooler in the box
  • Costs more than the Ryzen 5 7600X3D at the time of writing
Check price on Amazon for AMD Ryzen 9 9900X3D (opens in a new tab)

Premium Pick2 of 4

AMD Ryzen 9 9950X3D

The Ryzen 9 9950X3D adds a second eight-core die to the X3D formula, giving 16 cores for work while keeping 3D V-Cache for games.

Best for

Spending more than the Ryzen 9 9900X3D costs for the fullest feature set in this group.

Skip if

Choose another pick if you can't accept this: 170W rating calls for a large air cooler or a 280mm-plus AIO.
Check price on Amazon for AMD Ryzen 9 9950X3D (opens in a new tab)
AMD Ryzen 9 9950X3D

Why we like it

It suits a single machine that must game and render. Its 5.7GHz boost clock ranks second of 4 here, behind the Core i9-14900K (6GHz) and ahead of the Ryzen 5 7600X3D (4.7GHz). On core count it sits mid-pack at 16 cores: the Core i9-14900K offers 24 cores, and the Ryzen 5 7600X3D comes in at 6 cores.

On rated power it trails the group at 170W, while the Ryzen 5 7600X3D offers 65W. You also get a design aimed at both games and content creation. It needs an AM5 board (A620, B650, B850, X670 or X870 series) and DDR5 memory; a 600-series board may need a BIOS update first, so check the maker's CPU support list for the minimum version.

Budget for a dual-tower air cooler or a 240mm-plus AIO, since none is included. Only the Ryzen 9 9900X3D came close to it on price at the time of writing; it cost the most of the 4 picks.

Key specs

L3 cache
128MB
Max boost
5.7GHz
Cores / threads
16 cores
Rated power
170W
Threads
32
Socket
AM5
Memory
DDR5
Cooler in box
No
Integrated graphics
Yes

Pros

  • 128MB of L3 cache from 3D V-Cache
  • 5.7GHz maximum boost
  • 16 cores for encoding and background work
  • Integrated graphics for display output without a graphics card

Cons

  • 170W rating calls for a large air cooler or a 280mm-plus AIO
  • No cooler in the box
  • Rated power trails the Ryzen 5 7600X3D (65W)

The catch

It gives ground on rated power, where the Ryzen 5 7600X3D offers 65W.

Check price on Amazon for AMD Ryzen 9 9950X3D (opens in a new tab)

Lowest Rated Power3 of 4

AMD Ryzen 5 7600X3D

The Ryzen 5 7600X3D brings 96MB of L3 cache to a six-core AM5 chip at a 65W rating.

Best for

Buyers who put rated power first.

Skip if

Pass on it if 6 cores leave less headroom for streaming alongside games rules it out for your setup.
Check price on Amazon for AMD Ryzen 5 7600X3D (opens in a new tab)
AMD Ryzen 5 7600X3D

Why we like it

It is the cheapest way into AMD's cache-heavy gaming line on AM5. Its 96MB L3 cache ranks third of 4 here, behind the Ryzen 9 9900X3D (128MB) and ahead of the Core i9-14900K (36MB). Its 4.7GHz boost clock is the lowest in this group; the Core i9-14900K leads at 6GHz.

On core count it trails the group at 6 cores, while the Core i9-14900K offers 24 cores. Nothing else here matches its 65W rated power; the Ryzen 9 9900X3D comes closest at 120W. Like the Ryzen 9 9900X3D and Ryzen 9 9950X3D, it has an AM5 socket, while the Core i9-14900K uses an LGA1700 socket.

It needs an AM5 board (A620, B650, B850, X670 or X870 series) and DDR5 memory; check the board's CPU support list for the minimum BIOS version. No other pick here cost less at our last price check, and the Core i9-14900K was closest.

Key specs

L3 cache
96MB
Max boost
4.7GHz
Cores / threads
6 cores
Rated power
65W
Threads
12
Socket
AM5
Memory
DDR5
Cooler in box
No
Integrated graphics
Yes

Pros

  • 96MB of L3 cache from 3D V-Cache
  • 65W rating suits a modest air cooler
  • Integrated graphics for display output without a graphics card
  • 96MB of L3 cache on a six-core chip

Cons

  • 6 cores leave less headroom for streaming alongside games
  • No cooler in the box
  • Boost clock trails the Core i9-14900K (6GHz)

The catch

Boost clock is its weakest area, and the Core i9-14900K covers it better at 6GHz.

Check price on Amazon for AMD Ryzen 5 7600X3D (opens in a new tab)

Highest Boost Clock4 of 4

Intel Core i9-14900K

The Core i9-14900K is the last LGA1700 flagship with a 6.0GHz boost clock.

Best for

Buyers who put boost clock first.

Skip if

Choose another pick if you can't accept this: no cooler in the box.
Check price on Amazon for Intel Core i9-14900K (opens in a new tab)
Intel Core i9-14900K

Why we like it

Check your board has the latest BIOS for Intel's stability microcode. Its 36MB L3 cache is the smallest in this group; the Ryzen 9 9900X3D leads at 128MB. Its 6GHz boost clock is the highest here; the Ryzen 9 9950X3D comes next at 5.7GHz.

On core count it leads this guide at 24 cores, ahead of the Ryzen 9 9950X3D (16 cores). On rated power it sits mid-pack at 125W: the Ryzen 5 7600X3D offers 65W, and the Ryzen 9 9950X3D comes in at 170W. No other pick in this guide offers an LGA1700 socket; compare the Ryzen 9 9900X3D, which has an AM5 socket.

It is the only pick here with DDR4 or DDR5 memory; the Ryzen 9 9900X3D has DDR5 memory instead. It also comes with 8 performance and 16 efficient cores. It was priced above the Ryzen 5 7600X3D and below the Ryzen 9 9900X3D at the time of writing.

Key specs

L3 cache
36MB
Max boost
6GHz
Cores / threads
24 cores
Rated power
125W
Threads
32
Socket
LGA1700
Memory
DDR4 or DDR5
Cooler in box
No
Integrated graphics
Yes

Pros

  • 6GHz maximum boost
  • 24 cores for encoding and background work
  • Integrated graphics for display output without a graphics card
  • 8 performance and 16 efficient cores

Cons

  • No cooler in the box
  • L3 cache trails the Ryzen 9 9900X3D (128MB)
  • Costs more than the Ryzen 5 7600X3D at the time of writing

The catch

It gives ground on L3 cache, where the Ryzen 9 9900X3D offers 128MB.

Check price on Amazon for Intel Core i9-14900K (opens in a new tab)

How We Chose

Alex Morgan compared the manufacturer specifications, connectivity, warranty terms and compatibility of every pick. Figures come from the makers unless a third-party source is named; we did not test these products ourselves.

An Intel stock cooler mounted over the CPU socket inside a PC
An Intel stock cooler mounted over the CPU socket inside a PC
The figures behind the order
We lined up four processors on L3 cache, boost clock, core count and rated power from manufacturer specifications. We did not test them in-house, and all 9 compared fields are stated for every pick.
The shared baseline
All 4, from the Ryzen 9 9900X3D to the Core i9-14900K, state L3 cache, boost clock and core count and share integrated graphics.
Who each pick suits
The Ryzen 9 9900X3D for 3D V-Cache on a 12-core chip; the Ryzen 9 9950X3D for the top of this price range, adding 3D V-Cache on one of its two core dies; the Ryzen 5 7600X3D for the lowest rated power here (65W).
Price range
At our last check the picks ran from the Ryzen 5 7600X3D ($150 to $250) to the Ryzen 9 9950X3D ($500 to $1000).

What to Look for in a CPUs to Pair With an RTX 4090

Key buying criteria so you get the right fit the first time.

  1. L3 cache

    Here L3 cache runs from 36MB on the Core i9-14900K to 128MB on the Ryzen 9 9900X3D, a 256% spread. Start with the Ryzen 9 9900X3D if L3 cache decides it.

  2. How much boost clock you need

    The Core i9-14900K tops boost clock at 6GHz and the Ryzen 5 7600X3D sits lowest at 4.7GHz. The Core i9-14900K is the pick for boost clock.

    A desktop CPU seated in its motherboard socket with the retention frame open
    A desktop CPU seated in its motherboard socket with the retention frame open

  3. How much core count you need

    Across these 4 picks core count spans 6 cores (the Ryzen 5 7600X3D) to 24 cores (the Core i9-14900K). The Core i9-14900K is the pick for core count.

  4. Memory

    The Ryzen 9 9900X3D, the Ryzen 9 9950X3D and the Ryzen 5 7600X3D list DDR5; the Core i9-14900K lists DDR4 or DDR5. Settling memory first narrows 4 picks to 3 or 1.

  5. Cooler in box

    The Ryzen 9 9900X3D, the Ryzen 9 9950X3D, the Ryzen 5 7600X3D and the Core i9-14900K go without.

How to Choose a CPUs to Pair With an RTX 4090

By priority

PriorityConsiderWhy
Buyers who want 3D V-Cache on a 12-core chipRyzen 9 9900X3D3D V-Cache on a 12-core chip
Spending more than the Ryzen 9 9900X3D costs for the fullest feature set in this groupRyzen 9 9950X3DThe top of this price range, adding 3D V-Cache on one of its two core dies
Buyers who put rated power firstRyzen 5 7600X3DThe lowest rated power here (65W)
Buyers who put boost clock firstCore i9-14900KThe highest boost clock here (6GHz)

Scroll sideways to see every column.

Key specs side by side

The Ryzen 9 9900X3D leads on L3 cache at 128MB, ahead of the Ryzen 9 9950X3D at 128MB.

ProcessorL3 cacheMax boostCores / threadsRated power
Ryzen 9 9900X3D128MB5.5GHz12 cores120W
Ryzen 9 9950X3D128MB5.7GHz16 cores170W
Ryzen 5 7600X3D96MB4.7GHz6 cores65W
Core i9-14900K36MB6GHz24 cores125W

Scroll sideways to see every column.

By price at the time of writing

At our last check the cheapest pick, the Ryzen 5 7600X3D, sat in the $150 to $250 tier, 3 tiers in all up to the Ryzen 9 9950X3D at $500 to $1000; Amazon prices move, so recheck before buying.

Price tierProcessors
About $150 to $250Ryzen 5 7600X3D
About $250 to $500Core i9-14900K
About $500 to $1000Ryzen 9 9900X3D, Ryzen 9 9950X3D

Frequently Asked Questions

How does the Ryzen 9 9950X3D compare with the Core i9-14900K on boost clock?

The Core i9-14900K leads at 6GHz, with the Ryzen 9 9950X3D at 5.7GHz. The Ryzen 5 7600X3D closes the ranking at 4.7GHz.

Is the Core i9-14900K ahead of the Ryzen 9 9950X3D on core count?

The Core i9-14900K tops core count at 24 cores; the Ryzen 9 9950X3D follows at 16 cores, 50% apart. The spread runs down to the Ryzen 5 7600X3D at 6 cores.

Which has the lowest rated power: the Ryzen 5 7600X3D or the Ryzen 9 9900X3D?

Between the top two, it is 65W on the Ryzen 5 7600X3D against 120W on the Ryzen 9 9900X3D, a 46% difference. The spread runs down to the Ryzen 9 9950X3D at 170W.

Is the Ryzen 9 9950X3D worth paying more than the Ryzen 5 7600X3D?

The spec sheets show L3 cache (128MB against 96MB), boost clock (5.7GHz against 4.7GHz) and core count (16 cores against 6 cores) in its favour. It does not win everywhere: the Ryzen 5 7600X3D still leads on rated power (65W). The Ryzen 5 7600X3D sat in the $150 to $250 tier and the Ryzen 9 9950X3D in the $500 to $1000 tier when we checked, with 2 other picks between them; pay the difference only if L3 cache and boost clock decide your purchase.

What makes the Ryzen 5 7600X3D the Lowest Rated Power?

It earns the label for the lowest rated power here (65W). The Ryzen 9 9900X3D is next on rated power at 120W, so this pick's 65W is 46% further out. It makes sense for anyone who puts rated power first.

Do the Ryzen 9 9900X3D and the Core i9-14900K differ on socket?

The Ryzen 9 9900X3D, the Ryzen 9 9950X3D and the Ryzen 5 7600X3D use AM5; the Core i9-14900K uses LGA1700.

Bottom Line

Our first pick is the Ryzen 9 9900X3D, chosen for 3D V-Cache on a 12-core chip. Look at the Ryzen 9 9950X3D for the top of this price range, adding 3D V-Cache on one of its two core dies, the Ryzen 5 7600X3D for the lowest rated power here (65W) and the Core i9-14900K for the highest boost clock here (6GHz) if those matter more to you.

Play at 4K or with high settings to keep the GPU as the limit.

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About the author

PC Hardware Editor

Alex covers PC hardware, monitors, components, upgrades and peripherals for The PC Journal, with a focus on helping readers understand specifications, compatibility and meaningful product trade-offs.

Covers: Monitors, Graphics cards, Processors, PC components, Peripherals, Upgrades and compatibility

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