CPUz Reporting Memory At Wrong Speed

.Jay. · 28 Nov 2007 at 15:28

I've just put a new system together today with the following spec:

Q6600 @ 2.4GHz
Gigabyte P35 DS3P
Corsair Dominator 2x1GB PC2-8500 (1066MHz)

I've downloaded and run CPUz which reports the CPU running at 2.4GHz, however the memory is reported as running at 533MHz (as if a 1:2 divider is in use).

I've checked the BIOS and the multiplier setting is set to Auto and reports the memory speed correctly at 1066MHz.

Any idea what's causing CPUz to report the wrong speed? Have I missed an obvious setting?

Cheers,

Jay

Admiral Huddy · 28 Nov 2007 at 15:31

You should be able to select the DRAM frequency from the BIOS. Set it to 800MHz or set it to a 2:3 divider.

.Jay. · 28 Nov 2007 at 15:41

The BIOS frequency is reporting 1066Mhz which is correct. Its CPUz that seems to suggest its not running correctly.

Admiral Huddy · 28 Nov 2007 at 15:59

You are confusing the effective FSB of the CPU with the effective FSB of the system. They are not the same thing.

Your CPU, for example, operates with an FSB of 266MHz, but since these CPUs are Quad pumped they have an effective FSB speed of 1066Mhz (266 x 4 rounded up).

Your CPU is Double Data rate of the FSB 266 x 2 = 533MHz.. so on a 1:1 ratio (or syncronous), the speed of the RAM will run at 533MHz. By changing the ratio to 2/3 or the RAM speed to 800Mhz you are effectively running the RAM asynchronously. THis is to say, the RAM can operate at a different speed to that of the FSB.

Set the ratio to 2/3 or 800MHz.

Hope that helps..

Cob · 28 Nov 2007 at 16:11

Your memory is running at 1066mhz.

You have to double the CPU-Z reading as it's Double Data Rate memory.

So all is well. Tho you could do with tightening the timings a little

Admiral Huddy · 28 Nov 2007 at 16:53

you are correct my bad sorry

I was sure that CPU-Z reported the memory at double rate .. not single

(Ii'm going home)

.Jay. · 28 Nov 2007 at 20:42

Ok thanks for the reply, I understand what you're saying about the double data rate.

However, if you look at the SPD tab why does it say Max Bandwidth PC2-6400 when the RAM is PC2-8500?

Admiral Huddy · 29 Nov 2007 at 10:00

Ah this is because that the motherbaord lists PC2-6400 as being the highest memory speed that is rated and approved by JDEC. PC2-8500 and above are often known as Overclockers RAM because they exceed the JDEC specification.

iirc