Dell PowerEdge R750 Upgrade Guide: RAM and Storage Limits

Lifecycle and support

No longer sold new. Supported until June 30, 2028 (estimate).

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

RAM: registered ECC DDR4, 32 slots with two CPUs

The R750 has 32 full-size, 288-pin DDR4 DIMM slots: 8 channels per processor, 2 slots per channel, 16 slots per CPU. With only one CPU installed, just that CPU's 16 slots work, which halves every maximum below. No memory is soldered to the board.

It accepts registered ECC memory only. RDIMMs go up to 64 GB per module (2 TB with 32 slots filled). LRDIMMs go up to 128 GB (4-rank) or 256 GB (8-rank) per module, giving 8 TB with 32 slots filled, or half that with one CPU. UDIMMs are not supported.

The top speed is 3200 MT/s. Dell's spec table lists both 3200 and 2933 MT/s, while the memory population guide shows 3200 MT/s with one or two modules per channel. Dell doesn't explain the 2933 figure, so it may depend on your CPU or configuration. Dell's technical guide mentions 3DS DIMM support, but the manual's support matrix doesn't list it, so confirm before buying 3DS modules.

The server also supports Intel Persistent Memory 200 series modules (512 GB each). These are niche, need compatible CPUs, and Intel has discontinued Optane, so check availability first. The technical guide cites about 12 TB for a mix of persistent memory and LRDIMMs.

Buying tips

• Buy registered ECC DDR4 RDIMM or LRDIMM. Desktop-style unbuffered modules will not work.
• Check how many CPUs your server has before planning a full 32-slot build.
• Choose RDIMM unless you need more than 64 GB per module, since LRDIMMs are only needed for the very large sizes.
• Aim for 3200 MT/s modules, but expect that your CPU may decide the real speed.
• Skip persistent memory unless you already run it and have confirmed that you can still buy it.

Storage: fixed bay layout, SATA, SAS and NVMe drives

The chassis and backplane are chosen at purchase, so you can't add bays later. Front options are 12 x 3.5-inch SAS/SATA, or 2.5-inch layouts of 8 (NVMe only), 16 or 24 bays (SAS/SATA/NVMe). Some servers also have 2 or 4 optional 2.5-inch rear bays. These share rear space and cooling with the PCIe risers. Drives need Dell caddies.

For 2.5-inch drives, Dell lists SATA SSDs up to 3.84 TB, SAS SSDs up to 15.36 TB and NVMe U.2 SSDs (Gen3 or Gen4) up to 7.68 TB. Up to 24 NVMe drives are supported in total, and hot-swap NVMe is supported. Dell's documents don't state a thickness limit for 2.5-inch drives (7 mm vs 15 mm), so check the manual or your existing drives before buying.

For 3.5-inch bays, Dell's technical guide lists 7.2K HDDs up to 18 TB. The spec sheet's 192 TB maximum works out to 16 TB drives instead. Dell's documents disagree here, so treat 16 TB as the safe choice and confirm 18 TB drives before buying.

The only M.2 option is the optional BOSS-S1/S2 card, which holds two M.2 SATA SSDs (240 or 480 GB) in hardware RAID 1. Dell's documents don't state the M.2 length. The technical guide also lists 16, 32 or 64 GB microSD boot media, but module details are not confirmed. Both boot options are for the operating system, not bulk storage.

Buying tips

• Look at your server's front bays first. An NVMe drive only works in a bay that your backplane supports for NVMe.
• Buy Dell-caddied drives, or confirm that you have the right caddies.
• Confirm 2.5-inch drive thickness before ordering.
• Don't plan on adding M.2 drives to the motherboard. There are no M.2 slots there, only on the BOSS card.
• Don't add bays or swap the backplane as an upgrade. The layout is fixed at purchase.

How to upgrade

Before you start

• Find out how many CPUs your server has. One CPU means only 16 DIMM slots.
• Check which front backplane you have (8, 12, 16 or 24 bays, and which bays support NVMe).
• Use parts that Dell has validated for this system. Dell warns against installing PCIe devices that haven't been validated and tested.
• Have the owner's manual to hand for exact disassembly steps.
• Back up your data and note your current BIOS and firmware versions.

Steps

1. Back up your data
   Make a full backup of anything important before you open the server or change drives.
2. Power off and unplug
   Shut the server down properly, then unplug all power cables and wait for it to be fully off.
3. Ground yourself
   Use an anti-static wrist strap or touch bare metal on the chassis before handling parts. Hold modules and cards by their edges.
4. Open the server or reach the bay
   For hot-swap drives, you work from the front or rear bays with the right caddy. For memory and other internal parts, remove the top cover. Follow the owner's manual for the exact procedure.
5. Install the part
   Fit the memory module, drive in its caddy or boot card as the manual describes. Make sure each part is fully seated.
6. Close it up and reconnect
   Refit the cover or bay parts, reconnect the power cables, and power the server on.
7. Check that the system sees the part
   Look in the BIOS or system setup (or Dell's management tools) to confirm the new memory, drive or CPU is detected. If it isn't, power off and check the seating and your configuration.

Good to know

• Dell's documents don't give a CPU compatibility list, so this guide can't say which processors you can upgrade to.
• Dell's documents disagree on top memory speed (3200 vs 2933 MT/s) and on the largest 3.5-inch HDD (16 TB vs 18 TB).
• Dell lists 3DS DIMM support in the technical guide but not in the manual's support matrix.
• The 2.5-inch drive thickness limit and the M.2 module length are not stated in Dell's documents.
• Microsd boot media details and slot count are not confirmed.
• Related models such as the R750xs and R750xa may have different slot and bay counts, so don't apply this guide to them.

Frequently asked questions

How much RAM can the Dell PowerEdge R750 take?

With two CPUs and LRDIMMs, up to 8 TB (32 x 256 GB). With RDIMMs the limit is 2 TB (32 x 64 GB). With one CPU, you get half of each figure because only 16 slots work.

What type of RAM does the R750 use?

Registered ECC DDR4 in RDIMM or LRDIMM form, at up to 3200 MT/s. UDIMMs are not supported.

Can I use all 32 memory slots with one CPU?

No. Each CPU controls 16 slots, so a second CPU is needed to use all 32.

Does the R750 support NVMe SSDs?

Yes, on the right backplane. Up to 24 U.2 NVMe SSDs (Gen3 or Gen4, up to 7.68 TB each) are supported, and the 8-bay 2.5-inch version is NVMe only. Check which bays on your server are NVMe-capable.

Can I add M.2 SSDs to the R750?

Only through the optional BOSS-S1/S2 card, which holds two M.2 SATA SSDs (240 or 480 GB) in RAID 1 for booting. There are no M.2 slots on the motherboard.

What is the biggest hard drive the R750 supports?

Dell's technical guide lists 18 TB 3.5-inch 7.2K HDDs. The spec sheet's 192 TB maximum implies 16 TB drives, so Dell's documents disagree. Confirm before buying 18 TB drives.

Official documents and references

• Dell R750 memory specifications
  Module types, sizes and maximum capacity
• Dell R750 system memory guidelines
  Slot layout and speed by population
• PDF Dell PowerEdge R750 spec sheet (PDF)
  Bay options, drive capacities and BOSS card
• PDF Dell PowerEdge R750 technical guide (PDF)
  Drive types, NVMe support and boot media
• PDF Dell PowerEdge R750 installation and service manual (PDF)
  Disassembly steps and validated-parts warning
• PDF Dell PowerEdge R750 technical specifications (PDF)
  Expansion slots and system specifications
• Dell PowerEdge R750 manuals and documents
  Official manual downloads