HP EliteBook 840 G8 Upgrade Guide: RAM and SSD Options

Lifecycle and support

A current model: sold new and supported.

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

Memory (RAM): two DDR4 SO-DIMM slots, up to 64 GB

The EliteBook 840 G8 has two user-accessible DDR4 SO-DIMM slots that work in dual-channel. HP lists a maximum of 64 GB in total and a top speed of DDR4-3200 (3200 MT/s). HP lists 64 GB as 2 x 32 GB, so 32 GB per module is the practical limit, although HP doesn't state a per-module maximum directly.

HP's public spec page lists single modules or matched pairs: 4 GB (1 x 4), 8 GB (1 x 8 or 2 x 4), 16 GB (1 x 16 or 2 x 8), 32 GB (2 x 16) and 64 GB (2 x 32). The service manual text also lists mixed-size pairs such as 48 GB (32 + 16), 24 GB (16 + 8), 20 GB (16 + 4) and 8 GB (8 + 4). The two documents disagree here, so a matched pair is the safest choice for dual-channel performance.

If you mix modules of different speeds, the whole system runs at the slower speed. HP also says some third-party modules are non-industry-standard and recommends HP-branded memory for compatibility. HP doesn't say whether ECC or registered modules work, so stick to standard non-ECC DDR4 SO-DIMMs. We also couldn't confirm that no memory is soldered to the board, though the single-module configurations suggest all RAM sits in the slots.

Buying tips

• Buy DDR4 SO-DIMM modules rated for 3200 MT/s, not desktop DIMMs.
• Choose a matched pair (for example 2 x 16 GB) for dual-channel.
• Avoid mixing speeds; the slower module sets the pace for both.
• Consider HP-branded modules if you want to minimize compatibility risk.
• Skip ECC and registered modules; support isn't confirmed.

Storage: one M.2 2280 NVMe slot, up to 2 TB

The primary storage slot takes an M.2 2280 NVMe SSD. HP lists factory drives up to 2 TB, and the largest listed drive is a single-sided PCIe Gen 3 x4 NVMe TLC model that is 2.3 mm tall. Drives are 22 mm wide. No SATA M.2 drives are listed for this laptop, so choose NVMe.

The platform is specified for PCIe Gen 3. A Gen 4 drive should work no faster than a Gen 3 drive here, so there's no reason to pay extra for one. Most factory drives are x4, but the 128 GB drive and the Value drives are x2.

Some configurations ship with a 512 GB QLC drive paired with 32 GB of Intel Optane (the H10 hybrid). If yours has one, swap in a standard NVMe drive to get normal behavior. Also, some listings show an eMMC option alongside a 128 GB drive, and the wording is unclear. Check your exact SKU before assuming an M.2 drive is fitted. We found no second M.2 slot, 2.5-inch bay or memory card slot, so a bigger SSD means replacing the existing drive and moving your data across.

Buying tips

• Buy an M.2 2280 NVMe drive; single-sided is the safest fit, as HP's 2 TB drive is single-sided and 2.3 mm tall.
• Don't pay extra for PCIe Gen 4 speeds; this platform is Gen 3.
• Don't buy a SATA M.2 drive; none are listed for this model.
• If you have the Optane H10 model, plan to replace it with a standard NVMe SSD.
• Confirm your SKU has an M.2 drive and not an eMMC-only setup before buying.

How to upgrade

Before you start

• Check your exact SKU and read the HP maintenance and service guide for it.
• Back up your files, or plan to clone your old drive to the new one.
• Have the Windows recovery media or your license details ready if you plan a clean install.
• Buy the right parts: DDR4 SO-DIMM for memory, M.2 2280 NVMe for storage.
• Work on a clean, flat surface with a small screwdriver set suited to laptop screws.

Steps

1. Back up your data
   Copy important files to an external drive or cloud storage. If you're replacing the SSD, decide whether you'll clone it or reinstall Windows.
2. Power off and unplug
   Shut the laptop down completely (not sleep or hibernate) and unplug the charger and any accessories.
3. Ground yourself
   Touch a bare metal surface or use an anti-static strap before handling components, and hold memory modules and drives by their edges.
4. Open the case
   Remove the bottom cover as described in HP's maintenance and service guide for your SKU. Follow the owner's manual for the exact screws and order of removal, and don't force anything.
5. Install the new part
   For RAM, seat each SO-DIMM firmly in its slot until it is held in place. For the SSD, remove the old M.2 drive and fit the new 2280 NVMe drive in the same slot, following the manual for how it is secured.
6. Close the case
   Refit the bottom cover and screws, then reconnect power.
7. Check that the BIOS sees it
   Start the laptop and open the BIOS or firmware screen to confirm the new memory total or the new drive is listed. If a part isn't detected, power off, unplug, and reseat it.

Good to know

• HP's documents don't say whether ECC or registered memory works; stick to standard DDR4 SO-DIMMs.
• We couldn't confirm that no memory is soldered to the board, though the single-module configurations suggest it isn't.
• The 32 GB per-module limit is worked out from HP's 64 GB total, not stated directly.
• HP's public spec page and the service manual disagree on whether mixed-size memory pairs are supported.
• Some listings show an eMMC option, so check your exact SKU before assuming an M.2 drive is fitted.
• We found no second M.2 slot, 2.5-inch bay or memory card slot, but this isn't fully confirmed; check HP's maintenance and service guide for your SKU.
• No CPU upgrade route is described for this laptop.

Frequently asked questions

How much RAM can the HP EliteBook 840 G8 take?

Up to 64 GB in total, as two 32 GB DDR4 SO-DIMMs, at speeds up to 3200 MT/s.

Can I mix different RAM sizes in the EliteBook 840 G8?

HP's spec page lists only single modules and matched pairs, while the service manual text also lists mixed pairs such as 16 + 8 GB. A matched pair is the safest choice for dual-channel operation.

Does the EliteBook 840 G8 support PCIe Gen 4 SSDs?

The platform is specified for PCIe Gen 3, so a Gen 4 drive should gain nothing here. A standard M.2 2280 NVMe drive is the right choice.

What is the largest SSD I can put in the EliteBook 840 G8?

HP lists factory drives up to 2 TB in the M.2 2280 NVMe slot.

Can I add a second SSD to the EliteBook 840 G8?

We found no second M.2 slot or 2.5-inch bay for this laptop. Confirm with HP's maintenance and service guide for your SKU, but expect to replace the existing drive instead.

Can I upgrade the CPU in the EliteBook 840 G8?

We don't have a confirmed CPU upgrade route for this laptop, so we don't recommend buying a processor on the assumption that it can be swapped. RAM and SSD are the upgrades HP's documents describe.

Official documents and references

• HP Support: EliteBook 840 G8 specifications
  Official memory and storage configurations
• HP EliteBook 840 G8 service manual
  Product description with memory and drive details
• PDF HP EliteBook 840 G8 QuickSpecs (PDF)
  Drive dimensions, interface and capacity details
• iFixit: EliteBook 840 G8 memory module replacement
  Step-by-step memory guide
• HP EliteBook 840 G8 datasheet
  Memory and storage options listing