Dell XPS 15 9550 upgrade guide: RAM, SSD and CPU

Updated Oct. 20, 2026 · Written from this device's verified specifications

The XPS 15 9550 (late 2015, Skylake) is one of the friendlier laptops to upgrade: both memory slots are socketed and there is room for a fast NVMe drive. This guide explains what fits, the limits to watch for, and the two traps that catch people out — the battery that removes the 2.5 inch drive bay, and the cache drive sitting in the M.2 slot. Whatever you change, check the current price of the parts before you buy; prices move quickly and the listings on this page update automatically.

At a glance

    2x DDR4-2133 SO-DIMM (260-pin)2 × DDR4 SO-DIMM · up to 32 GB total · 2133 MT/s
    1x 2.5" SATA bay (7 mm height limit)HDD / SSD 2.5" (SATA) · max 7 mm thick
    1x M.2 2242/2280 M-key (NVMe/SATA)SSD M.2 2242 / M.2 2280 (NVMe / SATA)
    2 × SO-DIMM · DDR4up to 32 GB total1x 2.5" SATA bay (7 mm height limit)HDD / SSD 2.5" (SATA) · max 7 mm thick1x M.2 2242/2280 M-key (NVMe/SATA)SSD M.2 2242 / M.2 2280 (NVMe / SATA)
    Schematic of the upgradeable slots (not to scale). Check the owner's manual for their exact positions.

    Lifecycle and support

    A current model: sold new and supported.

    2015201720192021202320252027Today11 · Release · October 2015
    Filled dots: dates published by the manufacturer. Hollow dots: estimates from third-party sources.
    MilestoneDate
    Release
    First available to buy.    		 October 2015 Estimate Third-party report that the XPS 15 9550 became available for pre-order; no manufacturer release date statement found.
    Source ↗

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

    RAM: 2 slots, up to 32 GB at DDR4-2133

    Both SO-DIMM slots are socketed and reachable after removing the bottom cover — no 9550 configuration has soldered memory, so you can always get at both modules.

    What fits: DDR4 SO-DIMM, 260-pin, 1.2 V, non-ECC and unbuffered. The memory controller runs at DDR4-2133, and that is the speed ceiling. DDR4-2400 or DDR4-2666 modules physically fit and will work, but they always down-clock to 2133, so don't pay extra for faster rated sticks. ECC and registered modules will not work.

    Limits: 16 GB per slot, 32 GB total (2 x 16 GB), dual channel. Dell validates that figure; a single 32 GB stick is not supported and generally is not recognised, so plan on two 16 GB modules if you want the maximum. One retailer listing claims the machine has a single RAM slot — that contradicts Dell's own documentation and what people find inside the machine, so treat it as an error.

    Buying tip: match the two modules as a kit in the size you want. 32 GB mainly pays off for virtual machines, video work and large compiles; 16 GB is plenty for everyday use.

    Buying tips

    • DDR4 SO-DIMM 260-pin, 1.2 V, non-ECC unbuffered only.
    • DDR4-2133 is the cap — 2400/2666 sticks simply slow down to 2133.
    • Buy 2 x 16 GB for the maximum; a single 32 GB stick is not a route to 32 GB here.

    Storage: one 2.5 inch bay and one M.2 slot

    There are two internal storage connections, but which ones you can actually use depends on your battery.

    2.5 inch SATA bay: standard SATA (6 Gbps, backward compatible) and a strict 7 mm drive height limit. 15 mm drives do not fit. A 2 TB 7 mm SATA SSD is the realistic ceiling, though that figure is practical experience rather than a Dell-documented limit. Some SSD-only machines were shipped without the bracket and cable the bay needs, so check you have them.

    The critical caveat: the bay only exists in machines with the 56 Whr (3-cell) battery. On 84 Whr (6-cell) machines — 4K UHD touch models — the battery physically occupies the bay, and the M.2 slot becomes the only internal drive. Check which battery you have before buying a 2.5 inch drive; some owners of the larger battery deliberately downgrade it to get the bay back.

    M.2 slot: a single M-key connector with both 2242 and 2280 mounting positions, accepting NVMe or SATA M.2 drives. It is wired PCIe 3.0 x4, so Gen 4 drives work but run at Gen 3 speed — no need to hunt for a particular generation. Older firmware had trouble with some NVMe drives (the Samsung 970 EVO is the one people report problems with), so update the BIOS before or after installing a new drive.

    Cache drive warning: in HDD-plus-cache configurations, a 32 GB Intel Smart Response cache module is sitting in the M.2 slot. It is not a data drive — it holds no files you need to migrate. Disable the IRST caching first, then remove that module before fitting your new M.2 drive.

    RAID mode: the factory default SATA mode is RAID On (RST). Dell's administrator guide says switching to AHCI on this platform can cause a blue screen and is not recommended; install Windows with the RST driver loaded if your drive isn't visible during setup, or do a clean AHCI install rather than a mid-life switch. Whatever mode you install in must match the mode the machine boots in, or you will hit an INACCESSIBLE_BOOT_DEVICE error. The machine is UEFI only — avoid Legacy Option ROMs.

    Cloning order: disable the cache, image to external media, remove both the 32 GB module and the old HDD, install the new drive, restore the image — and do not boot with old and new drives installed together until at least one full boot cycle with only the new drive in place.

    Buying tips

    • Check your battery first: 84 Whr means no 2.5 inch bay at all.
    • 2.5 inch drives must be 7 mm tall; 15 mm drives will not close the case.
    • For M.2, any NVMe drive works — Gen 4 models just run at Gen 3 speed.
    • Flash the latest BIOS before installing a new NVMe drive.
    • If you have the 32 GB cache module, disable IRST caching and remove it before swapping drives.

    How to upgrade

    Before you start

    • Back up anything you care about — storage changes are the risky ones.
    • Power off completely and unplug the charger.
    • Ground yourself to avoid static damage to the board.
    • Open the case using the owner's manual for the exact disassembly steps for the XPS 15 9550.
    • Install the new part, then close the case.
    • Check in the BIOS/firmware that the part is detected, and flash the latest BIOS before or after any storage change.

    Frequently asked questions

    How much RAM can the Dell XPS 15 9550 take?

    32 GB, as 2 x 16 GB DDR4 SO-DIMMs at DDR4-2133. Both slots are socketed. A single 32 GB stick is not supported and generally isn't recognised.

    Can I upgrade the CPU in the XPS 15 9550?

    No. The processor is soldered to the motherboard — the Core i5-6300HQ or Core i7-6700HQ it came with — and the GTX 960M graphics are soldered too. There is no socket and no upgrade path.

    Does the XPS 15 9550 support NVMe SSDs?

    Yes. The M.2 M-key slot takes NVMe or SATA drives in 2242 or 2280 lengths, wired PCIe 3.0 x4. Update the BIOS first — older firmware had problems with some drives, notably the Samsung 970 EVO.

    Can I add a 2.5 inch SSD alongside an M.2 drive?

    Only if your machine has the 56 Whr battery. On 84 Whr units (4K UHD touch models) the battery fills the bay, leaving M.2 as the only internal storage. SSD-only machines may also be missing the bracket and cable.

    Will faster RAM run at full speed in the 9550?

    No. DDR4-2400 and DDR4-2666 modules fit and work, but they always down-clock to DDR4-2133 because the Skylake memory controller caps there.

    Do I need to change BIOS settings before installing a new SSD?

    Possibly. The machine ships in RAID On (RST) mode, and Dell's administrator guide warns that switching to AHCI can cause a blue screen. Install with the RST driver if the drive isn't visible during Windows setup, stay in UEFI mode, and make sure the SATA mode you install in is the mode the machine boots in.

    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.