Dell Precision Tower 3620 Upgrade Guide: RAM, SSD and CPU

Updated Oct. 9, 2026 · Written from this device's verified specifications

This guide covers adding memory, a bigger SSD or hard drive, and a faster processor in the Dell Precision Tower 3620 desktop. The short version: it takes up to 64 GB of DDR4, one M.2 NVMe drive plus SATA drives, and 6th or 7th Gen Intel Core and Xeon E3 processors, but nothing newer.

At a glance

  • RAM: 4 DDR4 slots on the Mini Tower, up to 16 GB per module and 64 GB total.
  • RAM speed is 2400 MT/s with a 7th Gen CPU and 2133 MT/s with a 6th Gen CPU.
  • Storage: one M.2 2280 NVMe slot (up to 1 TB listed) and two 3.5-inch bays that also hold 2.5-inch drives.
  • CPU: 6th/7th Gen Core and Xeon E3-1200 v5 (v6 needs BIOS 2.3.5 or newer); 8th Gen and newer are not supported.
  • Check whether you have the Mini Tower or the Small Form Factor (SFF) version first, as their slots and bays differ.
DDR4 DIMM slots4 × DDR4 DIMM · up to 64 GB total · 2400 MT/s
M.2 PCIe NVMe slotSSD M.2 2280 (NVMe) · up to 1 TB
Internal 3.5" bays (hold 3.5" or 2.5" drives)2 × HDD / SSD 3.5" / 2.5" (SATA)
CPU socket (LGA1151)LGA1151 (6th/7th gen) · Core 6th gen, Core 7th gen
CPU · LGA11514 × DIMM · DDR4up to 64 GB totalM.2 PCIe NVMe slotSSD M.2 2280 (NVMe) · up to 1 TBInternal 3.5" bays (hold 3.5" or2.5" drives)2 × HDD / SSD 3.5" / 2.5" (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 article dated 2015-10-01 reports Dell announcing the Precision 3620. The actual first on-sale date is unconfirmed.
Source ↗

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

RAM: DDR4, up to 64 GB

The Mini Tower has four DDR4 memory slots. Dell lists 4 GB, 8 GB and 16 GB modules, so the largest module is 16 GB and the most you can fit is 64 GB (4 x 16 GB). Memory is not soldered, so all of it can be upgraded.

Speed depends on your processor. Dell lists memory up to 2400 MT/s, but that needs a 7th Gen Core CPU. With a 6th Gen CPU the memory runs at 2133 MT/s. Both non-ECC and ECC memory are listed. Dell's documents don't say which CPU you need for ECC, but ECC normally only works with a Xeon E3 processor, so check your CPU before buying ECC modules. Registered (buffered) modules are not listed, so stick to ordinary unbuffered DDR4.

One version of Dell's online manual says the system has two DIMM slots, yet gives the same 64 GB maximum. Two slots can't reach 64 GB with 16 GB modules, so this is probably an SFF entry or an error. Dell's documents also don't say whether the slots take full-size DIMMs or laptop-style SO-DIMMs. A tower like this almost certainly uses full-size DIMMs, but compare against the modules already in your machine before you buy. If you only fit some of the slots, fill DIMM1 first.

Buying tips

  • Buy DDR4 DIMMs, not DDR3 and not SO-DIMMs, and confirm against your existing modules.
  • With a 6th Gen CPU, faster 2400 MT/s memory will just run at 2133 MT/s.
  • Only buy ECC memory if your processor is a Xeon E3 and you've confirmed it supports ECC.
  • Matching modules is the simplest way to avoid trouble when filling more than one slot.

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Storage: M.2 NVMe plus SATA bays

The Mini Tower has one M.2 slot for a 22 x 80 mm (2280) PCIe NVMe SSD, listed by Dell at up to 1 TB. Dell doesn't document the PCIe generation or lane width of this slot, so check the bandwidth of a fast NVMe drive against it before you buy; a very fast drive may not reach its rated speed. In system setup the slot appears as M.2 PCIe SSD-0.

There are also two internal 3.5-inch bays. They hold either two 3.5-inch drives or four 2.5-inch drives, using brackets or adapters (check that these are included on a used unit). The SATA controller runs at 6 Gb/s and supports RAID 0, 1, 5 and 10. Dell offered up to 4 TB per 3.5-inch drive and 512 GB for 2.5-inch SSDs, but those are the sizes sold at the time, not confirmed limits. Dell doesn't state a maximum thickness for 2.5-inch drives; standard 7 mm and 9.5 mm SATA drives are the likely fit, but verify.

The SFF version is different: it has one 3.5-inch bay, two 2.5-inch bays, one PCIe drive bay and one slim optical bay. An optional Dell Precision Ultra-Speed Drive (Duo) card, a PCIe x8 card holding one more PCIe SSD of up to 1 TB, was listed as coming soon, so confirm it is actually fitted if you're buying a used unit.

If you add several drives, remember the power supply is either 290 W or 365 W depending on configuration. Several drives plus a graphics card may be too much for the smaller one.

Buying tips

  • For the M.2 slot, buy a 2280 NVMe drive, not a SATA M.2 drive.
  • For the bays, a 2.5-inch SATA SSD is the easy option; make sure you have a bracket or adapter.
  • Use the 365 W power supply version if you plan to add many drives or a graphics card.
  • Check which chassis you have before ordering drives or brackets.

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CPU: 6th/7th Gen Core and Xeon E3

The processor is socketed and there is a single socket, so you can swap it. Dell's documents don't name the socket; the system uses the Intel C236 chipset, which pairs with LGA1151. Confirm this against Intel or Dell documentation before buying a processor.

Dell's spec sheet lists 7th Gen Core i7 (including the i7-7700K) and i5, 6th Gen Core i7, i5 and i3, and the Xeon E3-1200 v5 family. Xeon E3-1280 v6 support was added in BIOS 2.3.5, so v6 Xeons need that BIOS or newer. Dell lists no official maximum TDP. The i7-7700K is the highest-power part Dell names, and it is likely a 91 W part, but that isn't confirmed by Dell, so use the smaller PSU with caution. 8th Gen and newer CPUs are not supported.

Update the BIOS before installing a 7th Gen Core or Xeon v6 chip. Dell doesn't give a minimum BIOS for each CPU, so assume a recent one is needed and check the release notes on Dell's support page. Dell advises against jumping more than three BIOS versions at once, so install an intermediate version first if you're far behind. The latest BIOS found is 2.30.0 (13 May 2024); after installing it you can't go back to 2.3.0 or earlier.

Buying tips

  • Buy only 6th or 7th Gen Core, or Xeon E3-1200 v5/v6, and confirm the exact model on Dell's spec sheet.
  • Don't buy 8th Gen or newer; they won't work.
  • Choose a Xeon only if you want ECC memory; Core chips don't use it.
  • Update the BIOS first if the new CPU is 7th Gen or a Xeon v6.

How to upgrade

Before you start

  • Check whether you have the Mini Tower or SFF version; the slots, bays and power supply differ.
  • Back up your files before opening the case or changing drives.
  • Open Dell's owner's manual for your model so you can follow the exact disassembly steps.
  • For a CPU upgrade, check your BIOS version first and update it if needed. Suspend BitLocker before flashing and don't interrupt the update.
  • Check whether your current RAM, drives and CPU match what you plan to buy.

Steps

  1. Update the BIOS if you're changing the CPU
    Before installing a 7th Gen Core or a Xeon v6 processor, update the BIOS from Dell's support page. If you're several versions behind, install an intermediate version first. Suspend BitLocker beforehand.
  2. Back up and shut down
    Back up important data, shut Windows down completely and switch off the power supply if it has a switch.
  3. Unplug and discharge
    Unplug the power cord and all cables, then press the power button for a few seconds to drain leftover charge.
  4. Ground yourself
    Touch bare metal on the case before handling parts and avoid touching the gold contacts or chips.
  5. Open the case
    Remove the side cover following the owner's manual for your chassis.
  6. Install the part
    For RAM, fit modules into DIMM1 first. For an M.2 SSD, use the M.2 slot. For SATA drives, mount them in the bays with brackets and connect data and power cables. For a CPU, follow the manual's processor removal and installation procedures.
  7. Close the case and reconnect
    Refit the cover, then reconnect the cables and power.
  8. Check that the system sees it
    Enter the BIOS/system setup at startup. Confirm the correct RAM total, the drive (an M.2 drive appears as M.2 PCIe SSD-0) or the new CPU. Then boot into the operating system and check there too.

Good to know

  • Dell's documents don't state whether the memory slots take full-size DIMMs or SO-DIMMs; full-size DIMMs are assumed, so check your existing modules.
  • Dell's manuals disagree on the number of memory slots (four versus two); the Mini Tower has four.
  • Dell's documents don't name the CPU socket; these CPUs use LGA1151, which goes with the C236 chipset.
  • Dell gives no minimum BIOS for each CPU other than 2.3.5 for the Xeon E3-1280 v6, and no maximum CPU TDP.
  • The PCIe generation and lane width of the M.2 slot aren't documented.
  • Dell gives no thickness limit for 2.5-inch drives, and the listed drive capacities are sizes Dell offered, not confirmed limits.
  • The Ultra-Speed Drive (Duo) card was listed as coming soon, so don't assume a used unit has it.
  • After updating to BIOS 2.30.0 you can't go back to 2.3.0 or earlier.

Frequently asked questions

How much RAM can the Dell Precision Tower 3620 take?

The Mini Tower has four DDR4 slots and takes up to 16 GB per module, so the maximum is 64 GB. One version of Dell's manual mentions two slots, which is probably an SFF entry or an error, so check your own machine.

What RAM speed does it support?

Dell lists memory up to 2400 MT/s, but that needs a 7th Gen Core CPU. With a 6th Gen CPU the memory runs at 2133 MT/s.

Does the Precision Tower 3620 support an NVMe SSD?

Yes. The Mini Tower has one M.2 2280 PCIe NVMe slot, listed at up to 1 TB. Dell doesn't document the slot's PCIe generation or lanes, so a very fast drive may not reach its full speed.

Can I add more hard drives or SSDs?

The Mini Tower has two internal 3.5-inch bays, which hold either two 3.5-inch drives or four 2.5-inch drives, over SATA at 6 Gb/s. The SFF version has different bays, so check yours.

What is the fastest CPU I can fit?

Dell names the 7th Gen Core i7-7700K as the top Core part, and also lists Xeon E3-1200 v5 and (with BIOS 2.3.5 or newer) the E3-1280 v6. Dell doesn't state an official maximum TDP. 8th Gen and newer CPUs are not supported.

Do I need to update the BIOS before changing the CPU?

Yes, for a 7th Gen Core or Xeon v6 chip. Dell doesn't publish a minimum BIOS for each CPU other than 2.3.5 for the Xeon E3-1280 v6, so install a recent version and read the release notes.

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.