Dell OptiPlex 7040 Micro Upgrade Guide

Updated Oct. 19, 2026 · Written from this device's verified specifications

The Dell OptiPlex 7040 Micro is a small-form-factor desktop that is friendlier to upgrade than it looks. It has two laptop-style memory slots, an M.2 slot for an SSD, a 2.5-inch drive bay and a socketed processor. It is not the same machine as the OptiPlex 7040 Mini Tower or Small Form Factor: those siblings have 3.5-inch bays and an optical drive, and only those models support RAID. Here is what fits in the Micro, and what to watch out for.

At a glance

  • RAM: 2x DDR4 SO-DIMM, non-ECC. Dell's manuals say 16 GB total; Dell community, Kingston and MemoryCow confirm 32 GB (2x16 GB) works in practice. 2133 MT/s is the native speed.
  • Storage: one M.2 2280 slot (M-key, M.2 SATA or PCIe NVMe Gen3 x4) plus one 2.5-inch SATA bay. Both can be populated at the same time.
  • CPU: socketed LGA1151, but only 35 W 6th Gen Skylake T-series processors are supported. Standard 65 W desktop chips will not work here.
  • Before buying used, confirm the 65 W external power adapter is included.
2x DDR4 SO-DIMM (260-pin), non-ECC2 × DDR4 SO-DIMM · up to 32 GB total · 2133 MT/s
M.2 2280 Socket 3 (M-key) - SATA or NVMeSSD M.2 2242 / M.2 2260 / M.2 2280 (SATA / NVMe)
2.5" SATA bay (6 Gbps)HDD / SSD 2.5" (SATA) · max 7 mm thick · up to 2 TB
LGA 1151 (Socket H4) - 35 W T-series onlyLGA1151 (6th/7th gen) · Core 6th gen · max 35 W
CPU · LGA1151max 35 W2 × SO-DIMM · DDR4up to 32 GB totalM.2 2280 Socket 3 (M-key) - SATAor NVMeSSD M.2 2242 / M.2 2260 /M.2 2280 (SATA / NVMe)2.5" SATA bay (6 Gbps)HDD / SSD 2.5" (SATA) · max 7 mm thick ·up to 2 TB
Schematic of the upgradeable slots (not to scale). Check the owner's manual for their exact positions.

Lifecycle and support

No longer sold new. The manufacturer hasn't published an end-of-support date.

2015201720192021202320252027Today11 · Release · November 201522 · End of sale · 2021
Filled dots: dates published by the manufacturer. Hollow dots: estimates from third-party sources.
MilestoneDate
Release
First available to buy.		 November 2015 Estimate First availability. Trade press reported the announcement on 2015-10-20 (https://www.techpowerup.com/216887/dell-refreshes-its-optiplex-desktop-lineup), but availability itself is only documented as 2015-11 by the third-party entry above.
Source ↗
End of sale
No longer sold new by the manufacturer (Dell calls this 'End of Life', Lenovo 'Withdrawn').		 2021 Estimate No Dell source confirms this date.
Source ↗

Dates not listed haven't been published by the manufacturer or a reliable third party.

RAM upgrade

The OptiPlex 7040 Micro has two DDR4 SO-DIMM slots (260-pin), both user-accessible. There is no soldered memory, so anything you install is in removable modules. The memory must be non-ECC and unbuffered; ECC modules will not work.

The official numbers are a little confusing. Dell's original Owner's Manual caps each slot at 8 GB (16 GB total), and Dell's published spec sheet says 16 GB for the Micro model. However, Dell's own community, Kingston and MemoryCow all validate 2x16 GB = 32 GB, and that is what owners report working reliably. Treat 32 GB as the practical maximum and 16 GB as the figure Dell validated when the machine launched.

The native speed is 2133 MT/s. Faster DDR4 (2400 to 3200 MT/s) modules will work, but they simply run at the slower native speed, so don't pay extra for speed you can't use. Dell's documents don't name the voltage, but DDR4 SO-DIMMs at the standard 1.2 V are the norm here.

Buying tip: buy two matched modules to get dual-channel mode. The integrated HD 530 graphics uses system memory, so dual-channel gives a noticeable graphics boost compared with a single stick.

Buying tips

  • Two matched DDR4 SO-DIMMs for dual-channel performance.
  • Non-ECC, unbuffered only. ECC modules will not work.
  • 2133 MT/s is native; faster DDR4 will just downclock, so compare prices on the cheapest compatible sticks.

Storage upgrades (M.2 SSD and 2.5-inch drive)

The Micro gives you two storage options, and they can be used together: one M.2 SSD and one 2.5-inch SATA drive.

The M.2 slot is a Socket 3 M-key that accepts 2280-size drives, and shorter 2242 and 2260 drives fit if you move the screw to the correct position. 22110 drives do not fit. Both M.2 SATA and PCIe NVMe Gen3 x4 drives work; NVMe gives you the faster option, with a real-world ceiling around 3.5 GB/s from the Gen3 x4 link. Note there is a second, tiny M.2 2230 slot inside, but it is for the Wi-Fi/Bluetooth card only and cannot be used for storage. If you want to boot from NVMe, update the BIOS first and set the SATA operation mode to the correct setting in the firmware, or the drive may not show up as a boot device.

The 2.5-inch bay takes a standard SATA drive at 6 Gbps. Dell ships 7 mm drives, and 7 mm is the safe choice: MemoryCow advertises 9.5 mm compatibility, but check your caddy before buying a thicker drive. Dell validated hard drives up to 2 TB. Larger 2.5-inch SATA SSDs (4 TB and above) and big NVMe drives physically fit and are reported to work, but Dell has not validated them, so treat those as an unconfirmed gamble. There is no RAID support on the Micro model.

Buying tip: a small NVMe SSD for the OS plus a 2.5-inch SATA SSD for bulk storage is the classic setup for this machine, and the two can coexist.

Buying tips

  • Check the M.2 length you need: 2280 is standard, 2242/2260 need the right screw position.
  • Choose M.2 SATA or NVMe in the M-key slot; NVMe is the faster option.
  • For the 2.5-inch bay, 7 mm drives are the safe bet. Up to 2 TB is validated; bigger drives are unvalidated.

CPU upgrade

The processor sits in a socketed LGA1151 (Socket H4) slot, so it is replaceable in principle. In practice the choices are very limited. The Micro cooling solution is designed for 35 W chips only: Dell's spec sheet says 35 W for the Micro and 65 W for the larger models, so standard 65 W desktop processors are not supported and could overheat the tiny chassis.

The safe choices are 6th Gen Skylake T-series 35 W processors on the Intel Q170 chipset, such as the i5-6500T and i7-6700T (lower-end options like the Pentium G4400T and i3-6100T also use the same rules). Dell's documents don't name the socket; these chips use LGA1151.

7th Gen Kaby Lake processors fit physically in the same socket, but Dell's BIOS for the 7040 does not officially support them: that support belongs to the 7050. If you see this machine advertised with 7th Gen branding, treat 6th Gen T-series as the only safe assumption.

Because the Micro is quiet and tightly packed, a CPU swap is more work than a RAM or SSD upgrade and the real-world gain is often modest. It is worth doing mainly if your machine currently has a low-end chip and you can find a 35 W i5 or i7 T-series at a sensible price.

Buying tips

  • 35 W T-series only (i5-6500T, i7-6700T and similar). 65 W desktop CPUs are not supported.
  • 6th Gen Skylake is the safe choice. 7th Gen fits physically but is not officially supported.
  • Make sure the used machine includes its 65 W external power brick before paying.

Upgrade steps (general outline)

The same safe approach works for all three upgrades above:

1. Back up anything important first.
2. Shut the machine down and unplug it, including the external power adapter.
3. Ground yourself before touching components.
4. Open the case and install the new part. For the exact way to open the Micro and where the screws or latches are, follow the disassembly instructions in Dell's owner's manual for this model.
5. Close the case, reconnect power and start the machine.
6. Check that the BIOS sees the new part, and that the firmware reports the correct capacity for RAM or storage. If you added an NVMe drive, confirm it is recognised as a boot device after the BIOS update and SATA mode change mentioned earlier.

If the machine does not start or the part is missing in the BIOS, power off, unplug, reseat the component and try again.

How to upgrade

Before you start

  • Back up your data before any upgrade.
  • Power off and unplug the machine, including the 65 W external power adapter.
  • Ground yourself to avoid static damage.
  • Use Dell's owner's manual for the exact opening procedure for your unit.
  • After installing, confirm the new part appears in the BIOS before reinstalling your operating system or copying data.

Steps

  1. Step 1: Back up
    Save anything you cannot afford to lose. A storage upgrade is the moment things go wrong.
  2. Step 2: Power down and unplug
    Shut the computer down fully and disconnect the power adapter. Never work on an open machine that is plugged in.
  3. Step 3: Ground yourself
    Discharge static before handling memory, drives or the processor.
  4. Step 4: Open and install
    Open the case and fit the new part. Follow the owner's manual for the exact disassembly steps for this model.
  5. Step 5: Close and check
    Reassemble, plug in and start the machine. Check the BIOS reports the new RAM or storage correctly, and set the SATA operation mode if you added an NVMe boot drive.

Good to know

  • Dell's official documentation caps the Micro at 16 GB of RAM; community and memory-vendor testing shows 32 GB works. Both figures are quoted here so you can judge the risk.
  • Only 35 W T-series processors are supported in the Micro. 7th Gen CPUs fit the socket but are not officially supported by the 7040 BIOS.
  • Larger-than-validated drives (for example 4 TB 2.5-inch SSDs or very large NVMe drives) physically fit but are not validated by Dell.

Frequently asked questions

How much RAM can the Dell OptiPlex 7040 Micro take?

Dell's Owner's Manual and spec sheet say 16 GB total (8 GB per slot), but Dell's community, Kingston and MemoryCow all confirm that 2x16 GB = 32 GB works reliably in practice. Go with 32 GB if you need it; it has to be non-ECC DDR4 SO-DIMM.

Does the OptiPlex 7040 Micro support NVMe?

Yes. The M.2 Socket 3 M-key slot supports both M.2 SATA and PCIe NVMe Gen3 x4 drives. Update the BIOS first and set the correct SATA operation mode if you want to boot from an NVMe SSD.

Can I install a 7th Gen (Kaby Lake) processor?

It fits the socket physically, but Dell's BIOS for the 7040 does not officially support 7th Gen CPUs. That support belongs to the 7050. The safe choice is a 35 W 6th Gen Skylake T-series chip.

Can I use a normal 65 W desktop CPU like the i7-6700?

No. The Micro is designed for 35 W processors only; the larger 7040 models are the ones rated for 65 W. Look for the T-series versions, such as the i7-6700T.

Can I add a second drive to the OptiPlex 7040 Micro?

Yes. An M.2 SSD and a 2.5-inch SATA drive can be installed at the same time. There is no 3.5-inch bay, no optical drive and no RAID on the Micro model.

What size 2.5-inch drive fits?

Dell ships 7 mm drives in this bay and that is the safest choice. MemoryCow advertises 9.5 mm compatibility, so check your caddy before buying a thicker drive. Dell validated drives up to 2 TB; larger SSDs may work but are unvalidated.

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.