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Northwood Overclocking - Don't forget the memory

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Barryng

Member
Joined
Nov 16, 2001
I have been trying ever since the 1.8 Gig Northwood hit the streets to get past a 117 MHz FSB. Until a few days ago, every time I went higher than 117 MHz the system would become unstable and spontaneously reboot. I also ran into some catastrophic data integrity problem at speeds faster than 117 MHz. The higher the FSB speed, the more severe these problems became. At 133 MHz the machine would not even post no matter how high I took the CPU voltage.

I am now rock solid stable at 2.4 Gig (133 Mhz FSB). Here is what it takes and it is not much. BTW, my mobo is a TH7II.

We all know that the memory is "quad pumped" Therefore, if we are running at rated speed the dual channel RDRAM is at 4 X 100 X 2 = 800 MHz. Raising the FSB to 117 MHz raises the memory to 4 X 117 X 2 = 936 MHz. This turns out to be much too fast for my Samsung 800 MHz memory.

From the bios, I lowered the multiplier for the memory from 4X (400 MHz) to 3X (300 MHz). I then increased the FSB to 133 MHz. This results in the memory running at exactly its rated speed, 3 X 133 X 2 = 798 MHz. 133 MHZ also corresponds to 2.4 Gig for the 1.8 Gig Northwood.

I found that I also had to increase the voltage to 1.775 Volts. For good measure I also upgraded to MRNatural's outstanding 39C bios. CPU temperatures are now a little higher but the machine seems to be completely stable running SETI 24/7.

I hope this helps. I was previously reluctant to lower the memory multiplier because I did not realize that with the proper FSB, memory bandwidth will not be decreased.
 

VaTechHokies

Member
Joined
Feb 8, 2002
Location
Northern Virginia
Thanks for the good info RhoXS! I think a lot of this depends on which motherboard you have and what type of Samsung RDRAM you have. I know for myself, I have the memory set to 4X and am running my 16 device 2x256 Meg sticks of ram at PC1088 (136 FSB). You do, as you said, take a hit in memory bandwidth when you set the mem to 3X, but this allows you to up the FSB and raise the speed of the CPU.
 

Cooler666

Disabled
Joined
Jan 30, 2002
RhoXS that is exactly what i did with the same motherboard, processor and memory. Except i'm running it at 1.725V fine.
Also this is the only FSB (except at the stock FSB) where i have no cold boots.
 

batboy

Senior Moment
Joined
Jan 12, 2001
Location
Kansas, USA
I could not get my Samsung PC-800 memory to run at 4X above 125 FSB until I added a fan blowing onto the RDRAM for better ventilation. Now I can hit 133 FSB.