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Ok, I've overclocked my P4 2.26 Northwood up to 166GHz (my first shot at overclocking anything). I was happy about this since I assumed that this would bring my FSB in line with the memory speed on my DDR333 memory. However, my CPUZ report reads:

CPU(s)
Name: Intel Pentium 4
Code Name: Northwood
Specification: Intel(R) Pentium(R) 4 CPU 2.26GHz
Family / Model / Stepping: F 2 9
Extended Family / Model0 0
Brand ID: 9
Package: mPGA-478
Core Stepping: D1
Technology: 0.13 µ
Supported Instructions Sets: MMX, SSE, SSE2
CPU Clock Speed: 2839.7 MHz
Clock multiplier: x 17.0
Front Side Bus Frequency: 167.0 MHz <-- not sure why it says this since I confirmed that I set it to 166
Bus Speed: 668.2 MHz

Memory
DRAM Type: DDR-SDRAM
DRAM Size: 1024 MBytes
DRAM Frequency: 208.8 MHz
FSB
RAM: 4:5

CAS# Latency: 2.5 clocks
RAS# to CAS#: 3 clocks
RAS# Precharge: 3 clocks
Cycle Time (TRAS): 8 clocks
# of memory modules: 2

The DRAM frequency is showing at 208.8, which seems strange for DDR333, almost as if it's overclocked? Also, it looks like I have a FSB
RAM ratio which seems to confirm this, but I can't find any place in the CMOS to set (or unset) this.

I also noticed this which looked strange:

Mainboard and chipset
Motherboard manufacturer: Gigabyte Technology Co., Ltd.
Motherboard model: 8I848P-G, x.x
BIOS vendor: Award Software International, Inc.
BIOS revision: F5
BIOS release date: 08/19/2005
Chipset: Intel i865P/PE/G/i848P rev. A2
Southbridge: Intel 82801EB (ICH5) rev. 02
Sensor chip: ITE 8712
FSB Select: 533 MHz
Performance Mode: disabled

I have no idea what the FSB select is, and didn't see any option in the CMOS for it.
 

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For starters, read through the Intel Overclocking Guide linked in my signature. It should help you with many of your questions.


Basically, the external clock speed of your CPU is 133 MHz. This equates to 533 MHz FSB (133x4) and 2266 MHz (133x17) clock speed. DDR runs at twice the stock speed of the CPU, so 133x2=DDR266 or PC2100. But, since you are running DDR333 (166 MHz) MHz RAM, your BIOS sets a divider, which is the ratio of CPU:RAM. So, you're running at 133:166 = 4:5 as you're seeing. When you overclock to 166, the 4:5 divider remains, which is why you're seeing the higher RAM speed. There should be a place in your BIOS to select DDR266, which will get you to 1:1. The 4:5 divider may actually give you better performance, though.

That's a rundown on the basics. If it's all Greek to you, definitely check out the guide.
Please post back with any more questions you have.
 

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Discussion Starter #3
Quote:


Originally Posted by Taeric

For starters, read through the Intel Overclocking Guide linked in my signature. It should help you with many of your questions.


Basically, the external clock speed of your CPU is 133 MHz. This equates to 533 MHz FSB (133x4) and 2266 MHz (133x17) clock speed. DDR runs at twice the stock speed of the CPU, so 133x2=DDR266 or PC2100. But, since you are running DDR333 (166 MHz) MHz RAM, your BIOS sets a divider, which is the ratio of CPU:RAM. So, you're running at 133:166 = 4:5 as you're seeing. When you overclock to 166, the 4:5 divider remains, which is why you're seeing the higher RAM speed. There should be a place in your BIOS to select DDR266, which will get you to 1:1. The 4:5 divider may actually give you better performance, though.

That's a rundown on the basics. If it's all Greek to you, definitely check out the guide.
Please post back with any more questions you have.

Doh! I forgot all about the quad-pumped bus -- ofc it's 533.

As far as the divider, I finally found a Memory Frequency Setting that was set to AUTO. The options were AUTO, 2.0, and 2.5. I went in and changed it to 2.0 (2.5 gave the same results as AUTO) and now my divider is 1:1.

As you said, I can see how having a higher memory speed could help, but it only showed a 2% drop in performance. However, I'm wondering if maybe I can get tighter memory timings now...

And thanks!
 

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Since you're now running your RAM right at stock speed, you may be able to tighten the timings a bit. As you noticed with the minimal performance drop by removing the divider, it's very likely that you'll see a similar small performance gain by tightening the timings. Intel based systems do respond to tighter timings but not nearly to the degree that AMD systems do (the reverse is probably a more accurate statement - AMD systems suffer a greater performance loss than Intels with looser timings). Anyway, I would suggest that you try several different combinations and seeing what works best for your particular components.
 
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