Dell XPS Desktop 8940 Upgrade Guide: RAM, SSD and CPU

Updated Oct. 8, 2026 · Written from this device's verified specifications

This guide covers the three upgrades most XPS Desktop 8940 owners ask about: more memory, more storage and a faster processor. The short answer is that all three look user-upgradable, but memory speed is capped, there is only one M.2 storage slot, and the CPU choice is limited to the 10th and 11th Gen chips Dell lists.

At a glance

  • Memory: 4 DDR4 UDIMM slots, up to 32 GB per module and 128 GB total.
  • RAM speed is capped at 2666 MT/s with Core i3/i5 and 2933 MT/s with Core i7/i9.
  • Storage: one M.2 NVMe slot, one 3.5-inch SATA bay and two 2.5-inch SATA cages.
  • CPU: Dell lists 10th Gen and 11th Gen Core chips, up to 125 W (K/KF models).
  • The case and cooling are Dell's own design, so check the service manual before you start.
DDR4 UDIMM slots4 × DDR4 DIMM · up to 128 GB total · 2933 MT/s
3.5" SATA bayHDD / SSD 3.5" (SATA) · up to 2 TB
2.5" SATA cages2 × HDD / SSD 2.5" (SATA)
M.2 storage slotSSD M.2 2230 / M.2 2280 (NVMe) · up to 2 TB
CPU socketLGA1200 · Core 10th gen, Core 11th gen · max 125 W
CPU · LGA1200max 125 W4 × DIMM · DDR4up to 128 GB total3.5" SATA bayHDD / SSD 3.5" (SATA) · up to 2 TB2.5" SATA cages2 × HDD / SSD 2.5" (SATA)M.2 storage slotSSD M.2 2230 / M.2 2280 (NVMe) · up to 2 TB
Schematic of the upgradeable slots (not to scale). Check the owner's manual for their exact positions.

RAM: four full-size DDR4 slots, up to 128 GB

The XPS 8940 has four DDR4 slots that take full-size desktop DIMMs (UDIMM), not laptop SO-DIMMs. Dell lists module sizes of 4, 8, 16 or 32 GB, with a maximum of 128 GB (4 x 32 GB). The smallest configuration Dell lists is 8 GB. Dell's manual lists these combinations: 1x8, 2x4, 1x16, 2x8, 1x32, 2x16, 2x32, 4x16 and 4x32 GB.

Speed is the main catch. Dell says the computer ships with 3200 MHz memory, but it runs at no more than 2666 MT/s with a Core i3 or i5 and 2933 MT/s with a Core i7 or i9. Dell's product page and its manual's configuration list quote slightly different figures (3200 versus 2666/2933), so treat the lower numbers as the real ceiling. Faster kits will not help. The 11th Gen chips may allow higher speeds, but Dell's documents don't say so, so don't count on it.

Dell's documents only mention UDIMMs and don't say whether ECC or registered memory works. Plan on standard unbuffered, non-ECC DIMMs. A single module runs in single-channel mode, so use matched pairs for dual-channel performance.

Buying tips

  • Buy standard desktop UDIMMs, not SO-DIMMs.
  • Buy matched pairs (2 x 8 GB or 2 x 16 GB, for example) for dual-channel.
  • Don't pay extra for kits rated above 3200; the system can't use the speed.
  • Avoid ECC or registered memory; Dell doesn't document support for it.

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Storage: one M.2 NVMe slot plus SATA bays

There are four places to put drives. The single M.2 storage slot takes a 2230 or 2280 PCIe Gen3 x4 NVMe SSD, up to 2 TB per Dell. It also accepts Intel Optane memory (2280 size). A second M.2 2230 slot is reserved for the WiFi/Bluetooth card and can't be used for storage.

For extra capacity, the case has one 3.5-inch SATA bay (SATA AHCI, up to 6 Gbps, up to 2 TB documented) and two 2.5-inch SATA cages that hold HDDs or SSDs. The 2.5-inch cages ship empty with only one SATA extension cable, so a second drive may need an extra SATA cable. Dell doesn't state a thickness limit for the 2.5-inch cages. Dell's published maximum is 2 TB per drive type, and larger drives are not documented.

An older Dell support article says NVMe is not supported, but Dell's current manual and product page both list NVMe M.2 SSDs as supported. The older article appears to be outdated.

Buying tips

  • For the fastest drive, pick a PCIe Gen3 x4 NVMe SSD in 2280 or 2230 size.
  • For bulk storage, a 2.5-inch or 3.5-inch SATA drive is the easy route.
  • Pick a 2 TB drive or smaller; Dell doesn't document larger ones.
  • Budget for an extra SATA cable if you fill more than one SATA bay.
  • Don't buy an M.2 card for the WiFi slot; it can't hold storage.

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CPU: 10th and 11th Gen Core, up to 125 W

Dell lists 10th Gen Core processors (i3-10100 up to i9-10900K, including the F/KF variants) and 11th Gen Core processors (i5-11400 up to i9-11900K, including F/KF). The K and KF models are rated 125 W; the others are 65 W. At the top end, the i9-10900K has 10 cores and 20 threads, and the i9-11900K has 8 cores and 16 threads.

Dell's documents don't name the socket. These processors use LGA1200, which also fits the H470 chipset Dell lists, but verify this before buying. Dell's service manual has a processor removal section, which suggests the CPU is a replaceable part.

The chassis and cooling are Dell's own design rather than a standard ATX layout. Dell doesn't say whether the stock cooler suits a 125 W chip, so be cautious with K-series upgrades. Also confirm which CPU generation your unit has before you order parts.

Buying tips

  • Stay within the 10th and 11th Gen chips Dell lists.
  • Confirm your current CPU model and generation first.
  • 65 W (non-K) chips are the safer choice for the stock cooling and power supply.
  • If you pick a 125 W K/KF chip, check your power supply, especially if you also plan a graphics card.

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How to upgrade

Before you start

  • Find your current CPU, RAM and drive details in Windows (Task Manager and System Information) so you know what you are replacing.
  • Check which power supply you have. Dell offers 360 W and 500 W units, and the 500 W unit supports a graphics card up to 225 W; the 360 W unit is more limited.
  • Have the Dell XPS 8940 service manual open for exact disassembly steps.
  • Get a small screwdriver, an anti-static wrist strap (or touch bare metal to ground yourself), and any extra SATA cables you need.
  • Back up your important files before opening the case.

Steps

  1. Back up your data
    Copy important files to an external drive or cloud storage before you change any hardware, especially if you plan to swap or clone a drive.
  2. Power off and unplug
    Shut the computer down fully, unplug the power cable and all other cables, then hold the power button for a few seconds to drain leftover charge.
  3. Ground yourself
    Work on a clean, hard surface and touch bare metal on the case, or wear an anti-static strap, before handling components.
  4. Open the case
    Follow the Dell service manual for removing the side cover and any internal parts in the way. The case is Dell's own design, so don't assume a standard ATX layout.
  5. Install the new part
    For RAM, fit matched DIMMs in the slots as the manual describes. For storage, use the M.2 slot (not the WiFi slot) or the SATA bays, adding data and power cables as needed. For a CPU, follow the manual's processor removal and installation procedure.
  6. Close up and reconnect
    Refit any parts you removed and the side cover, then reconnect the cables and power.
  7. Check that the system sees the part
    Start the computer and enter the BIOS setup screen to confirm the new memory, drive or processor is detected. If anything is missing, power off, unplug and recheck the connections.

Good to know

  • Dell's documents don't name the CPU socket. These processors use LGA1200, which matches the H470 chipset Dell lists, but verify before buying.
  • Dell's documents don't say whether ECC or registered memory works; stick to standard unbuffered DIMMs.
  • Dell's documents quote the memory speed differently (3200 MHz on the product page, 2666/2933 MHz in the manual). Expect the lower, capped speeds.
  • Dell doesn't say whether 11th Gen CPUs allow faster RAM than the stated limits.
  • An older Dell support article says NVMe is unsupported; Dell's current manual and product page say it is supported.
  • Dell doesn't state a thickness limit for the 2.5-inch cages, and drives larger than 2 TB are not documented.
  • The chassis and cooling are Dell's own design, so a 125 W K/KF chip may need extra care. Confirm your unit's CPU generation and power supply before buying parts.

Frequently asked questions

How much RAM can the Dell XPS Desktop 8940 take?

It has four DDR4 UDIMM slots and supports up to 32 GB per module, for a maximum of 128 GB (4 x 32 GB). Use matched pairs for dual-channel performance.

What speed of RAM does the XPS 8940 support?

Dell says the system ships with 3200 MHz memory but runs it at 2666 MT/s with Core i3/i5 and 2933 MT/s with Core i7/i9. Dell's manual lists 2666/2933, so buying faster kits gives no benefit.

Does the XPS 8940 support NVMe SSDs?

Yes. The M.2 storage slot takes a 2230 or 2280 PCIe Gen3 x4 NVMe SSD, up to 2 TB per Dell. An older Dell article says NVMe is unsupported, but Dell's current manual and product page contradict it.

How many drives can I install in the XPS 8940?

There is one M.2 storage slot, one 3.5-inch SATA bay and two 2.5-inch SATA cages. The 2.5-inch cages ship empty with only one SATA extension cable, so you may need extra cables.

What CPUs can I upgrade to in the XPS 8940?

Dell lists 10th Gen Core chips from i3-10100 to i9-10900K and 11th Gen chips from i5-11400 to i9-11900K, including F/KF variants. Dell doesn't name the socket; these CPUs use LGA1200, so verify before buying.

Can I add a graphics card to the XPS 8940?

Dell says the 500 W power supply supports a graphics card up to 225 W, while the 360 W unit is more limited. Check which supply you have first.

Official documents and references

This guide was written with AI assistance from the compatibility data PartsPrices verified against the manufacturer's documents. Always check your exact model and the owner's manual before buying or opening your computer.