Intel Core2Duo 2.4Ghz @ 3.0Ghz 1333MhzFsb
Twin-X Corsair 1GB DDR2 667 @ 533
Asus P5B-E Plus

I can successfully OC my CPU to 3.0Ghz but the DRAM Freq decreaase to 533Mhz. When I set DRAM freq back to 667Mhz, system hangs! Why? The RAM and MOBO supports 667Mhz. I never mess with the rest of the mem timings. Do I need to increase Mem/CPU voltage?? Help??

Intel Pentium 4 2.8@23.2GHZ
1GB DDR400 Dual Channel RAM
ASUS P4P800-X
PowerColor X1600 PRO 512MB DDR2 AGP
SB Audigy 2
Maxtor 120GB+250GB 16MB 7200RPM

Things might be clearer for you if you'd discuss real numbers rather than theoretical numbers.

You'll get best performance out of your system if the CPU & RAM run at the same bus speed...aka, 1:1 ratio

The E6600 default clock setting is 9 x 266MHz, therefore the RAM should run at 266MHz (DDR533), REGARDLESS of the fact that it's DDR667!

If you crank the CPU up to 9 x 333MHz, your RAM should run at 333MHz (DDR667). But to attain this speed, the RAM setting in the BIOS should be DDR533, NOT DDR667. If you have it set to DDR667, the RAM will try to run at about 416MHz, but since it's not capable of that speed, the system will lock up.

Keep the RAM setting at DDR533 at all times.

but will RAM set at DDR-2 533 slow the system down, even by a margin? I'm using Vista Home Premium. help. thank you

Intel Pentium 4 2.8@23.2GHZ
1GB DDR400 Dual Channel RAM
ASUS P4P800-X
PowerColor X1600 PRO 512MB DDR2 AGP
SB Audigy 2
Maxtor 120GB+250GB 16MB 7200RPM

I just explained it to you. If you set the RAM to DDR553, then increase the CPU bus to 333MHz, the RAM will run at DDR667.

Download CPUZ & check the real world settings for yourself. Check the Memory tab for the speed that your RAM is actually running at. Download, unzip, then click on CPUZ.exe.....

http://www.cpuid.com/cpuz.php

In other words, what jam is saying is that those DRAM frequency ranges in your BIOS namely: DDR2 533, 667, 800 & 1066MHz are actually meant to work like (CPU:DRAM) ratio dividers (if you are familiar with this). See how it's broken down below.

- 533:533 = 1:1 ⇒ DRAM Frequency @ 533MHz

- 533:667 = 4:5 ⇒ DRAM Frequency @ 667MHz

- 533:800 = 4:6 ⇒ DRAM Frequency @ 800MHz

- 533:1066 = 4:8 ⇒ DRAM Frequency @ 1066MHz

Correspondingly, when you had your CPU @ 1333MHz (333 x 9) & you figured that by setting the DRAM Frequency @ 667MHz that you'd be balancing (1:1) things up, what you failed to realize was that you just inadvertently selected the 4:5 (CPU:DRAM) ratio, that being the reason for the 416MHz quoted by jam.

Hopefully, I didn't make it even more complicated that it should have been for you ;-)

Also that board isn't marketed here in the US, but there is a review of its overclocking here. As with most mothernoards with the 965 chipset, the FSB is able to scale high up there, as those guys were able to get it boot into Windows at 500MHz but not without dropping the multipler a couple of notches.

However, with the stock multipler & air cooling, it got as far as ~340MHz (not far from where your is sitting) & still not bad at all, considering the Core 2 Extreme X6800 that retails for between 900-$1000 is rated @ 2.93GHz. And literally having a $1000 CPU cranking away in any home computer, is by all means something to relish - until its value is severly depreciated come Groundhog Day........LOL

Lastly, the two things I see in the way of your E6600 scaling very much higher than the current 3GHz speed is the RAM & the cooling, you can try to raise the voltage (in 0.025) to see if you can squeeze a little more MHz, but I don't expect your RAM to allow you to very far. You should have gotten some PC26400 (DDR2800) instead of the PC25400 Twin-X from Corsair.

Good Luck!

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