PC2-6400 instead of PC2-8500?

[ChristianV]

Hello

I noticed that CPU-Z shows that I have 4x 1GB PC2-6400 @ 1.8V
However, I have bought 2 KHX8500D2K2/2GB, so 4x 1GB 1066Mhz.
Thus, I set the timings, clock speed and the voltage manually:
5-5-5-18; DDR2-1066; 2.2V
CPU-Z still shows me that I have 4 PC2-6400 400MhZ@1.8V(in the SPD tab)
In the "Memory"-Tab however, it shows that the Ram is running at 534MHz which is correct.

Any ideas why CPU-Z shows me different values?

thanks in advance.

 

[Blain]

Originally posted by: ChristianV
Any ideas why CPU-Z shows me different values?

A reporting glitch would be my guess.

 

[SunnyD]

That's because there is no such thing as a "JEDEC DDR2-1066 PC8500" standard. The highest official DDR2 spec standard is PC6400 @ 800MHz. 1066MHz ram is simply "factory 'guaranteed' overclocked PC6400" ram that has been tested to "overclock" stably with specified voltage and timings at 1066MHz. Absolutely no memory manufacturer can set a standard SPD autoprofile to anything higher than 800MHz. Now on the other hand, EPP profiles do allow it, but "Auto timings" in a motherboard won't use EPP (it's a separate setting on most mobos). In CPU-Z, the only tab you care about in terms of memory is the Memory tab.

Side note: SPD means "Serial Presence Detect". It's a small EPROM on the memory module which stores factory information about the module and what it supports - NOT what the memory is currently operating at. It's a "guideline table" to allow motherboards to autodetect what usually is the greatest common denominator for motherboard compatibility in terms of speed, timing and voltage.

 

[n7]

Originally posted by: SunnyD
That's because there is no such thing as a "JEDEC DDR2-1066 PC8500" standard. The highest official DDR2 spec standard is PC6400 @ 800MHz. 1066MHz ram is simply "factory 'guaranteed' overclocked PC6400" ram that has been tested to "overclock" stably with specified voltage and timings at 1066MHz. Absolutely no memory manufacturer can set a standard SPD autoprofile to anything higher than 800MHz. Now on the other hand, EPP profiles do allow it, but "Auto timings" in a motherboard won't use EPP (it's a separate setting on most mobos). In CPU-Z, the only tab you care about in terms of memory is the Memory tab.

Side note: SPD means "Serial Presence Detect". It's a small EPROM on the memory module which stores factory information about the module and what it supports - NOT what the memory is currently operating at. It's a "guideline table" to allow motherboards to autodetect what usually is the greatest common denominator for motherboard compatibility in terms of speed, timing and voltage.

Beautifully explained.

 

[ChristianV]

wow, thanks a lot for that detailed response!

I'm not sure if I got it right, but does that mean that I have to manually adjust the settings for my Ram if I go higher than PC6400?

 

[Zap]

Originally posted by: n7
Beautifully explained.

+1

I just want to add that memory companies will "bin" their modules, and sell better ones as a higher speed module. Any RAM that needs higher than JEDEC voltage (1.8v for DDR2, 1.5v for DDR3) is basically "factory overclocked." With what CPU-Z reports in the SPD and EPP, this can sometimes be evident. For instance, my OCZ VISTA Upgrade memory (except mine has copper heatspreaders that are starting to discolor) is sold as DDR2-800 at 1.8v-2.0v. The SPD reports up to DDR2-667 speeds only.