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Overclocking Help


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Hi :hello: ,

I just recently had a look through all mags and read a section on PC overclocking and have decided to try and overclock my PC by 20%.

I have a Socket 478 Celeron (Codename: Northwood) running at 2.4Ghz (100*24.0) on a ECS 661FX-M mobo. It is possible to change my FSB (CPU Frequency), but not my multiplier (set to 24.0)

Sensor Info (Taken from BIOS) [see Fig 9]:

• Core Voltage: 1.48V - 1.525V

• DDR Voltage: 2.60V - 2.62V

• CPU Temp: 38°C - 41°C

• CPU Fan Speed: 2596RPM - 2636RPM

I went into my BIOS (Phoenix - AwardBIOS CMOS Setup Utility) [see Fig 1] and found its overclocking page (under Frequency/Voltage Control) and was overwhelmed by all the confusing options [see Fig 2].

The following options were changeable without having to change any other settings [see Fig 3]:

• 'Auto Detect DIMM/PCI Clk';

• 'Spread Spectrum';

(both of which are Enabled and only have the two options, Enable and Disable.)

The following options I could change once I changed the 'Clock Control by' control from Auto to Manual [see Fig 4 and 5]:

• 'Async AGP/PCI/SRC Clk' (with options: 'DISABLE'¹², '66/33/100MHz', '80/40/100MHz'¹, '72/36/100MHz'¹);

• 'CPU Frequency' (A 'DEC' Number between 100-253, set to 100. I did the Maths and to increse the CPU Speed by 20% I have to set this number to 120 [120*24.0= 2.88GHz]);

• 'CPU:DRAM Frequency Ratio' (with options: 'SPD'²³, '1:1', '3:4', '3:5', '1:2') [see Fig 7];

Then there was this display at the bottom of all the options [see Fig 2, 3, 4]

• 'DRAM Frequency' (a display showing 200MHz when 'CPU:DRAM Freq Ratio' set to 'SPD' and the 'CPU Freq' set to the default 100, and when I set the 'CPU Freq' to 120 the 'CPU:DRAM Frequency Ratio' changed to 1:1 and this display showed 120MHz but when I changed the 'CPU:DRAM Freq Ratio' to '3:5' the display showed 200MHz again) [see Fig 5, 6 and 8].

¹When I changed the CPU Frequency to 120 these options are still show but are not selectable; ²Default Option; ³Disappeared when I set the CPU Frequency to 120

All I want to know is if I change the CPU Frequency to 120 what else do I need to change to reflect that?

Do I need to change the 'CPU:DRAM Freq Ratio' so that the 'DRAM Frequency' stays the same?

Do I need to make the DRAM frequency double the CPU Frequency as it was before? Or is there some pattern that i can't see?

Would looking a a SiSoft Sandra report of my Processors and/or other computer parts help me determine the correct DRAM speeds and if my CPU would be damaged if I overclocked at 20%?

Fig Links:


Thankyou in advanced :thumbup ,


P.S. I am being so in-depth because this is my favorite computer and I don't want it to get broken

Edited by atyndall
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whats a divider? and what info do i need to look at in CPU-Z to dertime my RAMs max speed?

I thing its max speed without errors might be 200MHz (See Screenshot of cpu-z)

P.S. i really don't want to do anything to my com's hardware or anything physical and i only have one stick of ram in my com

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  • 2 weeks later...

Celeron 2.4? That's a very overclockable CPU. 20% (2.88GHz) is nothing. This one can easily go up to 50% (3.6GHz) with stock cooling, and near 70% (4GHz+) with a better HSF.

First of all, disable spread spectrum. This will increase RFI but result in a more stable overclock.

Keep the AGP/PCI clocks at the default 66/33MHz.

The limiting factor with your board, is the very limited amount of DRAM divider ratios available. You need to increase the CPU frequency, while keeping the RAM frequency around 200MHz (you can increase this a bit to overclock the RAM, but will likely start getting RAM errors with cheap RAM when going over 5%). 120MHz with 3:5 will give 200MHz for the RAM and 2.88GHz for the CPU, and this overclock will most definitely work unless you were very unlucky. However, 20% is not a very large performance increase - barely noticeable. You could try 125/3:5 which will give 208.3MHz for the RAM (depending on the quality, it may or may not work at this point) and a full 3GHz CPU.

Once you've determined that it's stable, you can try going for 50% - 150/3:4 which gives 200MHz RAM and 3.6GHz CPU.

The main limitation is that you have only 4 dividers available, and none of them are particularly good.

I was lucky to get this configuration:


Clock is set at 167, divider is 5:8 which gives 267MHz on the RAM (very lucky this DDR400 RAM could take the 67% overclock to DDR533). Cooling is *not* stock.

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Clock is set at 167, divider is 5:8 which gives 267MHz on the RAM (very lucky this DDR400 RAM could take the 67% overclock to DDR533). Cooling is *not* stock.

2.4@4.0GHz is indeed a pritty OC. I remember to OC a Celeron(2) 600@1130MHz :).

By the way; You are only OCing the ram with 33% ;)

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