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HP OMEN 40L Gaming Desktop GT21: RAM, storage and CPU upgrade guide

Mis à jour le 30 octobre 2026 · Rédigé d'après les spécifications vérifiées de cet appareil

The OMEN 40L GT21 is a full-size gaming desktop with four RAM slots, two M.2 NVMe slots and a socketed CPU, so it upgrades well. The catch: the GT21 name covers several boards. Some are DDR4-era Intel machines (GT21-0000/0067), others are DDR5-era Intel or AMD machines (GT21-1000/1100). RAM and CPU parts differ between them and are physically incompatible, so before you buy anything, look up your exact product number on the label on the case and check HP's support page for your unit. Everything below tells you what to look for and where the limits are.

En bref

  • 4 DIMM slots, up to 128 GB total on DDR5 boards (HP's DDR4 documentation disagrees on the maximum)
  • 2 x M.2 2280 NVMe PCIe Gen4 x4 slots, plus a 3.5-inch SATA drive option
  • Socketed CPU: LGA1700 on Intel boards, AM5 on AMD boards — CPU and RAM support depend on your sub-model
  • RAM speed is capped by your CPU: 65 W chips run memory slower than 125 W K-series chips
4x DIMM (DDR4 ou DDR5, selon la carte)4 × DDR4 / DDR5 DIMM · jusqu'à 128 GB au total · 5200 MT/s
2x M.2 2280 NVMe + SATA 3.52 × SSD / HDD M.2 2280 / 3.5" (NVMe / SATA)
4 × DIMM · DDR4/DDR5jusqu'à 128 GB au total2x M.2 2280 NVMe + SATA 3.52 × SSD / HDD M.2 2280 / 3.5" (NVMe / SATA)
Schéma des slots extensibles (pas à l'échelle). Vérifiez le manuel de l'utilisateur pour leur position exacte.

Cycle de vie et support

Un modèle actuel : vendu neuf et supporté.

202220232024202520262027Aujourd’hui11 · Commercialisation · 10 mars 2022
Points pleins : dates publiées par le fabricant. Points creux : estimations de sources tierces.
JalonDate
Commercialisation
Premier jour de vente.		 10 mars 2022 Officiel GT21-0000 series (e.g. GT21-0000ng, 675H8EA) — earliest HP-published 'Release date' for the 0000 generation; first availability of the series.
Source ↗

Les dates non listées n'ont pas été publiées par le fabricant ou une source tierce fiable.

RAM: 4 DIMM slots, but DDR4 or DDR5 depends on your board

The OMEN 40L GT21 has four DIMM sockets (desktop 288-pin UDIMM, not laptop memory), arranged as two per channel. Nothing is soldered, so all four slots are yours to use.

The big fork is memory generation. GT21-0000 and GT21-0067 models are DDR4 boards; GT21-1000 and GT21-1100 models are DDR5 boards. DDR4 and DDR5 modules look similar at a glance but cannot be swapped for each other, so match what your board takes.

Capacity: DDR5 boards accept 8, 16 or 32 GB modules and go up to 128 GB total (4 x 32 GB). For DDR4 boards the sources disagree: one HP manual quotes a 64 GB maximum, while HP's page for the DDR4 GT21-0067 says up to 128 GB with 32 GB modules on 64-bit systems. If you own a DDR4 model and want more than 64 GB, treat that figure as unconfirmed and check with HP for your product number before buying.

Speed: DDR5 boards go up to DDR5-5200 and DDR4 boards up to DDR4-3733 — but only with 125 W K-series CPUs. With 65 W CPUs the supported speed drops (HP lists lower figures such as DDR4-3467, and DDR5 down to 3600–4400 on some models). Kingston notes that faster modules simply run at a lower speed here, so there is no point paying for very high-rated kits expecting full speed.

Type: non-ECC, unbuffered UDIMM only. Server or ECC memory is not supported.

Install memory in matched pairs for dual-channel performance, and follow HP's populate order DIMM 4-2-3-1. Mismatched capacities will work but only run in dual-channel up to the size of the smaller stick.

Buying tips:
- Find your product number first and buy DDR4 or DDR5 to match.
- Prefer matched kits (same capacity, same model) in pairs.
- Don't overspend on high MHz; your CPU sets the ceiling.

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Storage: two M.2 NVMe slots plus a 3.5-inch SATA bay

There are two M.2 socket 3 (key M) 2280 NVMe slots, PCIe Gen4 x4, for standard 22 x 80 mm drives. These are NVMe-only: M.2 SATA SSDs are not supported in these slots.

Alongside them you get a SATA option in the 3.5-inch form factor — HP sells the machine with 1 TB or 2 TB 7200 rpm SATA hard drives and notes that dual storage is available on select models. HP's pages don't list exactly how many drive bays the chassis provides or their thickness limits, so check the service guide or manual for your exact model before buying a hard drive or a 2.5-inch SSD.

On capacity, HP's factory configurations top out at 2 TB per M.2 drive (WD_BLACK PCIe Gen4 NVMe SSDs in 512 GB, 1 TB and 2 TB). Larger M.2 drives may well work, but HP doesn't document them for this machine, so treat anything above 2 TB as untested.

For reference, the wireless card is a replaceable M.2 2230 module in its own socket — it is not a storage slot and won't fit a 2280 drive.

Buying tips:
- Any M.2 2280 NVMe (PCIe Gen4) drive fits; Gen4 x4 is the bus, so Gen4 drives are the natural match.
- Skip M.2 SATA drives — the slots don't support them.
- Adding a second M.2 SSD is the simplest capacity upgrade; pair it with a SATA hard drive if you need cheap bulk storage.

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Comment mettre à niveau

Avant de commencer

  • Back up your data before touching anything.
  • Look up your exact product number on the case label and check HP's support page for your unit — DDR4/DDR5 and the CPU socket depend on it.
  • Shut down the PC, switch the power supply off and unplug the power cable.
  • Ground yourself (touch the metal chassis or use an anti-static strap) so you don't damage parts with static.
  • Open the case side panel and lay the desktop on its side; the exact screws and latches are shown in HP's owner's manual for your model.
  • Install the new part, close the case and reconnect power.
  • Start the PC and check that the BIOS/firmware reports the new memory, drive or CPU correctly.

Bon à savoir

  • Verify your exact product number before buying any part — the GT21 range spans DDR4 and DDR5 boards and two CPU sockets.
  • Where HP's own documents disagree (DDR4 maximum RAM, the LGA 1200 typo, factory CPU lists), this page says so rather than guessing.

Foire aux questions

How much RAM can the OMEN 40L GT21 take?

Up to 128 GB (4 x 32 GB) on the DDR5 boards. For DDR4 models the sources disagree: one HP manual says 64 GB, HP's DDR4 GT21-0067 page says up to 128 GB with 32 GB modules. Check your exact product number with HP before buying large DDR4 kits.

Is the OMEN 40L GT21 DDR4 or DDR5?

Both exist. GT21-0000 and GT21-0067 models are DDR4; GT21-1000 and GT21-1100 models are DDR5. The modules are physically incompatible, so buy the type your board takes.

Does the OMEN 40L GT21 support M.2 SATA SSDs?

No. The two M.2 2280 sockets are NVMe (PCIe Gen4 x4) only. M.2 SATA drives won't work in them; use a 3.5-inch SATA drive for bulk storage instead.

Can I upgrade the CPU?

Yes, the CPU is socketed — LGA1700 on Intel boards, AM5 on AMD boards. HP only guarantees its listed processors, and cooling/power limits (125 W on Intel, up to 170 W on AM5 OC boards, 65 W on non-OC) constrain what makes sense.

Do I need to update the BIOS before upgrading?

Possibly. HP's documents don't state this for every configuration, so check the support pages for your exact product number before installing a newer CPU.

What RAM speed will I actually get?

It depends on your CPU, not just the board. 125 W K-series chips allow up to DDR5-5200 or DDR4-3733; 65 W CPUs run memory slower (HP lists figures such as DDR4-3467 and DDR5-3600–4400 on some models). Faster modules clock down automatically.

Documents officiels et références

Ce guide a été rédigé avec l'aide de l'IA à partir des données de compatibilité que PartsPrices a vérifiées par rapport aux documents du fabricant. Vérifiez toujours votre modèle exact et le manuel de l'utilisateur avant d'acheter ou d'ouvrir votre ordinateur.