Corsair Twin2x2048-640C4 on Abit IP35-pro

[Mutley]

Hi,

I have the above mentioned RAM install on an Abit IP35-Pro motherboard.
Looking at CPU-Z I see two tabs of interest - Memory and SPD.

Under the Memory tab I see:
Frequency : 399Mhz
FSBRAM : 2:3
CAS# Latency : 5.0 clocks
RAS to CAS Delay : 5
RAS precharge : 5
Cycle Time (Tras) : 18

Under SPD I see:
CAS latency : 4.0
RAS to CAS : 4
RAS Precharge : 4
Tras : 12
Trc : 22
Command Rate : 2T

My understanding was that this RAM should run at 4-4-4-12. Could someone explain the difference between the Memory and SPD tabs in CPU-Z? Is the memory tab showing what timings the RAM is running at, and the SPD tab showing what it could run at, or visa-versa?

If its that my RAM is running at 5-5-5-18, why is that, as the motherboard is running with everything set as default in the BIOS (auto in otherwords).

Thanks!

[Yellowbeard]

The SPD settings are set at the industry standards defined by JEDEC so that the memory will boot with the most different MOBOs. To run the 4,4,4,12 settings you will need to set them manually in your bios. Also, set the memory voltage to 2.1v

In CPU-Z, the SPD timings shown on the SPD tab are the preset timings programmed onto the RAM. The MEMORY tab shows what the memory is actually running.

[Mutley]

Cool, thanks for that YellowBeard.

In the BIOS settings, I see a whole host of possible memory settings, with names like tRAS, and so on - could you point me to any resources which would explain what those terms mean?

Many thanks!

[Yellowbeard]

This is a good start, the Corsair Memory Basics Presentation.

Also, www.rojakpot.com has a good database of definitions in their bios opt guide.