Updated on November 8, 2026.
SPD stands for Serial Presence Detect. It’s a set of information stored on a memory module that tells your PC what the module is and which settings it supports. Your PC reads it during startup. You can read it in Windows with CPU-Z to identify a stick or check its saved profiles.
What SPD tells the PC
On a typical removable module, a small chip stores the SPD information. DDR5 modules use an SPD hub that includes storage for it. The PC’s firmware reads the information as it starts, then uses the CPU and board’s limits to choose and test memory settings. See Kingston’s DDR5 overview.
| SPD field | What you can learn |
|---|---|
| Memory type and size | Whether the module is DDR4 or DDR5, for example, and how much memory it holds. |
| Manufacturer and part number | Which module is in that slot. Some fields can be empty. |
| JEDEC timings | Standard settings the firmware can use, including supported speeds and timings. |
| XMP or EXPO profile | An optional saved profile for a particular speed and timings on a compatible system. |
How to read SPD in CPU-Z
- Get CPU-Z for your Windows PC from CPUID’s official download page.
- Open the SPD tab and choose a slot from Memory Slot Selection. Switch between slots to see each module the tool can read.
- Check Module Size, Part Number, and the Timings Table. The table shows settings saved on that module.
- Open the Memory tab to see the active settings. For DDR memory, a DRAM Frequency near 3,000 MHz corresponds to about 6,000 MT/s. See our guide to MT/s and MHz.
If the SPD tab lists a lower speed than your kit’s box, look for an XMP or EXPO column. A kit may have a standard profile and a faster optional profile. The Memory tab shows what’s in use. See our guide to Intel XMP 3.0 for how those profiles work.
What to check when SPD is blank or missing
Try each slot. An empty slot has no module to report, and some laptops or firmware don’t expose every module’s SPD to a Windows tool. Check the installed memory total in Task Manager or the BIOS. If the system also reports less memory than you installed or shows a startup memory error, check the PC or motherboard’s memory support and diagnostics.
Frequently asked questions
What does the number of SPD modules mean?
In a hardware report, it usually counts the module records the tool could read. Check the per-slot details and the system’s installed memory total to see what the PC recognizes.
When does a PC read RAM SPD?
During startup, the firmware reads the module information before Windows loads. It uses it to help set up and test the memory.
Does the SPD tab show the speed my RAM is running at?
It shows saved module information and profiles. Open CPU-Z’s Memory tab for the current frequency and timings.
What does SPD not detected mean?
The tool couldn’t read SPD for that slot. Check for an empty slot or a system that limits access, then confirm the installed memory total. A startup error or missing installed capacity warrants a separate memory check.