Core 2 Duo overclocking

Preamble

Everybody knows that Core 2 Duo is a perfect processor for overclocking. I have becoming legacy E6300 model. Since I also have 800MHz memory, P5B Deluxe motherboard which is a overclockers choice and TT BigTyphoon CPU cooler I decided to play a little with my FSB frequency.

Overclocking procedure

The reason why I started this in the first place was low 3DMark06 results – only 8600 points. I saw 12k for similar PC configurations.

On ASUS motherboard you can find overclocking tweaks under Advanced -> Jumperfree Configuration -> AI Tuning -> change to Manual. I locked PCI frequency at 33.33MHz and PCI-E frequency at 101MHz. Then I was able to increase FSB frequency from 266MHz up to 320MHz without any other tweaking in cooling or voltage. Then system started to become unstable: application crashes and BSODs. I used same 3DMark06 for testing purposes.

Next step was  replacement of poor North Bridge radiator with Zalman NB47J. I also sticked small radiators from my old Zalman VF700-Cu I took from a drawer onto unipolar CPU transistors which are always getting hot on P5Bs. It let me become stable with 340MHz. Next was updating a BIOS. I had old 0405 version. Surprisingly enough BIOS v1238 allowed me to increase frequency up to 400MHz! I think it comes from the fact that ASUS improved automatic voltage regulation in later versions. I stopped at this point because further increase of FSB will force memory modules to work at not-supported frequencies which I don’t want to deal with.

Overclocking results

parameter: old value, new value, %
memory throughput: 4.77Gb/s, 6.77Gb/s, 40%
cpu frequency: 1.86GHz, 2.80GHz, 50%
3dmark: 8600, 10600, 25%

CPU temperature and undervoltage

Unfortunately I got too high CPU temperatures. 68C idle and more than 84C under load. To solve this problem I changed thermal grease. It gave me 8 degrees. And lowered CPU voltage from 1.5 to 1.1 by 0.05 step. Beware of motherboard setting up VCore lower than you actually pointed on 0.05V. It means that if you set 1.35V you will actually get 1.3V. You can check that under Power -> Hardware Monitor after reboot. Each time I tested CPU with S&M ‘cache 1’ test. It gave me highest CPU temperatures. Then I launched OCCT (Overclock Checking Tool) 3.1.0. Its ‘CPU Linpack’ test just burns everything. But test ended with ‘Error Detected’ message. Increasing voltage by 0.05 solved the problem and test went just fine. After an hour of CPU burning Core Temp 0.99.8 showed me 40C idle and 51C load. It’s astonishing how motherboard overvolt CPU.

Additional info

FSB / Memory throughput:
266 MHz, 4.77Gb/s
320 MHz, 5.13Gb/s
340 MHz, 5.51Gb/s
350 MHz, 5.66Gb/s
400 MHz, 6.77Gb/s

Voltage / CPU idle and load temp:
1.5 59C/77C (S&M)
1.45 53C/68C (S&M)
1.4 51C/64C (S&M)
1.35 47C/60C (S&M)
1.3 45C/56C (S&M)
1.25 43C/54C (S&M)
1.2 42C/51C (S&M)
1.15 41C/48C (S&M)
1.15 40C/51C (OCCT)
1.1 39C/46C (S&M)

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