Memory Timings Displayed by CPU-Z Question

[shan2752]

I just did my first build and have some questions interpreting CPU-Z Memory Diagnostics:

My Hardware is as Follows:

CPU INTEL|CORE 2 E6600 2.4G 775 R - Retail

ASUS P5N32-SLI SE Deluxe Socket T (LGA 775)

CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Unbuffered Dual Channel Kit System Memory Model TWIN2X2048-6400C4 - Retail

Under CPU-Z's Memory Tab it shows that my memory is running at 5:5:5:18

But under the SPD Tab it says that each modules timing is 4:4:4:12

Which timings are correct? Do I need to set the timings manually in the Bios?

Any input would be greatly appreciated! Thanks!

 

[suzukii]

I hope you get an answer for this.

8O Can someone explain these new memory timings to me as if I were a 3rd grader PLEEEEZE????
Tanx go 2 da brave wunz.

 

[darkstar782]

The SPD timings are the timings your memory is rated for

The other timings are the timings your memory is at.

Change them in the BIOS

 

[prolfe]

The third-grader explanation of memory timings is this: smaller numbers mean faster speeds.

The sixth-grader explanation of memory timings is that each number represent a number of microseconds (or maybe milliseconds) that the memory has to wait between operations.

I don't understand it any better than that, hope it helps!

 

[Mondoman]

The SPD timings are the timings your memory is rated for

The other timings are the timings your memory is at.

Change them in the BIOS

Well, sort of.

First, the SPD is just a little EEPROM (memory) in the DIMM into which the manufacturer programs one or more sets of timing info. These are timings that the DIMM will work at under standard conditions, they are NOT the maximum speed or necessarily even the rated speed that the DIMM will work at. Your MB reads this info when it boots up and uses it to "auto set" the bus speed and timings of the RAM, unless you have over-ridden the auto setting in the BIOS. For example, if the RAM is sold as DDR2-800 RAM, inside the SPD there might be a DDR2-800 set of timings, a DDR2-667 set of timings, and a DDR2-533 set of timings. The MB will usually choose the fastest bus speed it supports (e.g. DDR2-800).

Oftentimes, a DIMM is certified for (and sold as supporting) faster timings than those in the SPD for a given bus speed. Usually, this requires setting the RAM's voltage to a higher-than-standard level in the BIOS. Therefore, you need to find out from the manufacturer the full details of the certification, including the RAM voltage. Often, instead of standard DDR2 voltage of 1.8V, the voltage used for certification is in the 1.9-2.1V range. If you want to run your RAM at the certified speed, set the memory voltage to the specified level in the BIOS, then manually set the other timings via the BIOS.

Finally, it may turn out that the DIMM is physically capable of running fine at even faster bus speeds and/or shorter timings than what the manufacturer has certified. This is "overclocking" the RAM.