Memory timings in CPU-Z : Memory and SPD tab discrepancy – What do they mean


When I run CPU-Z in my netbook, in the memory tab, the timings displayed are 5-5-5-15, but in the SPD tab, the timings are 5-5-5-18 (JEDEC #3).

What do the differences in the timings between the tabs mean? Which is the timing followed by the computer?

The netbook is a Samsung NP-N150 (Intel Atom N450 1.66 GHZ processor). It has one RAM slot. It contains one 2 GB DDR2-800 RAM stick -"Elixir" brand, made by Nanya. (This is not the default RAM stick. This was upgraded from its default 1 GB stick.) The OS is Windows 7 Starter, 32-bit.

CPU-Z Screenshots

Memory tab:
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SPD tab:
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CPU-Z report – memory section:


Northbridge Intel Atom Host Bridge rev. 00
Southbridge Intel NM10 rev. 02
Memory Type DDR3
Memory Size 2048 MBytes
Channels Single
CAS# latency (CL) 5.0
RAS# to CAS# delay (tRCD) 5
RAS# Precharge (tRP) 5
Cycle Time (tRAS) 15
Row Refresh Cycle Time (tRFC) 44
Command Rate (CR) 2T
MCHBAR I/O Base address 0x0FED14000
MCHBAR I/O Size 4096

Memory SPD

DIMM # 1
SMBus address 0x50
Memory type DDR2
Module format SO-DIMM
Manufacturer (ID) Nanya Technology (serial number removed)
Size 2048 MBytes
Max bandwidth PC2-6400 (400 MHz)
Manufacturing date Week 18/Year 09
Number of banks 2
Data width 64 bits
Correction None
Nominal Voltage 1.80 Volts
EPP no
XMP no
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 3.0-3-3-9-12 @ 200 MHz
JEDEC #2 4.0-4-4-12-16 @ 266 MHz
JEDEC #3 5.0-5-5-18-23 @ 400 MHz

Best Answer

SPD Tab shows the available timings for that memory, Memory Tab shows actual timings set and used by the bios.