Here’s a useful way of finding out how many memory slots are occupied on the motherboard of a machine without removing the cover, as well as how much installed physical memory is supported.

We can use the dmidecode command to reveal your systems DMI table, which contains details of the systems hardware.

Personally, I always check for available memory banks the easy way, with the ever reliable 'check with eyeballs' method. Or, if I dont have physical access, I normally use the model name and number to check the hardware specs online. Commands to Check Memory Use in Linux cat Command to Show Linux Memory Information Entering cat /proc/meminfo in your terminal opens the /proc/meminfo file. This is a virtual file that reports the amount of available and used memory.

There are a whole load of DMI types we can look at – a full table of those at the end of this article.

In this particular case, we are interested in memory – type 16 ‘Physical Memory Array’ will show us how much memory is supported and DMI type 17 will reveal details of currently installed memory.

So, first off:-

dmidecode -t 16

Maximum Capacity shows us the maximum amount of memory can be installed in the machine. Number of devices tells us how many slots there are on the motherboard – in this case, 8.

Now we can interrogotate DMI type 17 – ‘Memory Device’ to show us details of installed memory

dmidecode -t 17

Each module installed will be listed with the the information given above. If we just want to know how many modules are installed and what size they are, we only really need the Size: – so we use grep

dmidecode -t 17 grep Size

From this we can see that 8x 2048MB modules are installed – so all the slots on the motherboard are populated.

There is plenty of other useful information that can be retrieved using dmidecode, including

-t1 System

-t2 Base Board

-t3 Chassis

-t4 CPU

-t9 PCI slots

Linux Command To Check Memory Slots

Full SMIBIOS Specification

Linux Command Check Memory Slots Free

1 System
2 Base Board
3 Chassis
4 Processor
5 Memory Controller
6 Memory Module
7 Cache
8 Port Connector
9 System Slots
10 On Board Devices
11 OEM Strings
12 System Configuration Options
13 BIOS Language
14 Group Associations
15 System Event Log
16 Physical Memory Array
17 Memory Device
18 32-bit Memory Error
19 Memory Array Mapped Address
20 Memory Device Mapped Address
21 Built-in Pointing Device
22 Portable Battery
23 System Reset
24 Hardware Security
25 System Power Controls
26 Voltage Probe
27 Cooling Device
28 Temperature Probe
29 Electrical Current Probe
30 Out-of-band Remote Access
31 Boot Integrity Services
32 System Boot
33 64-bit Memory Error
34 Management Device
35 Management Device Component
36 Management Device Threshold Data
37 Memory Channel
38 IPMI Device
39 Power Supply
40 Additional Information
41 Onboard Device