There are hellova articles in the Internet on OC in general and particularly on overclocking CPUs on ASUS P5B Deluxe and other P965 chipset motherboards. So here I’ll just post my results and BIOS configuration, along with some of my findings.
I was able to overclock FSB from 266 to 400 with x8 CPU multiplier. Which effectively means 3200MHz frequency as opposed to 2400 stock.
BIOS settings
JumperFree Configuration
CPU Frequency: 400
DRAM Frequency: DDR2-800MHz
PCI Express Frequency: 101
PCI Clock Synchronization Mode: 33.33MHz
Spread Spectrum: Disabled
Memory Voltage: 1.9V
CPU VCore Voltage: 1.525V
NB VCore: 1.25V
SB VCore (SATA, PCIE): 1.5V
ICH Chipset Voltage: 1.057V
CPU Configuration
CPU Ratio Setting: 8
C1E Support: Disabled
Max CPUID Value Limit: Disabled
Vanderpool Technology: Enabled
CPU TM Function: Enabled
Execute Disable Bit: Enabled
North Bridge Configuration
Basic Timings: 5-5-5-15-5
Additional Timings: 42-10-10-10-25
Static Read Control: Disabled
The most important thing to realize about OC on P5B Deluxe is the necessity of manual memory timings set up. Initially I wasted a lot of time trying to OC over 350 FSB with no luck. After changing timings to mentioned above I easily OCed to 400. I can’t explain why you need to set them like this. I just found them in the Internet and it works for me.
What was also new for me is that CPU with x6 multiplier and 400 FSB won’t work with the same voltage as x9 on 266. It’s the same frequency, however, CPU always init on x9 multiplier and only after power up system changes it to configured in BIOS. It means that if you want to lower CPU voltage by changing multiplier, then don’t expect voltage to decrease to initial values.
Another interesting fact is that with C1E Support setting enabled you will get less performance and less marks in CPU dependent benchmarks like 3DMark. C1E Support can lower CPU frequency when CPU idles. But it seems that it also reduces its performance under load.
I also left CPU TM Function (throttling) enabled for safety purposes.
For those who want to increase FPS in games I want to say that CPU and memory OC won’t give you any significant performance boost in games. For example in Unigine benchmark for 266 FSB, 2.4GHz CPU I get 37.9 average FPS. And for 400 FSB, 3.2GHz I get 38. I agree that for some games it will make difference but it’s not worth it. Don’t torture your system.
Results
266 FSB, 2.4GHz CPU:
Max temperature in linpack (OCCT) 54C (measured by Core Temp)
SiSoft Sandra Memory Throughput 5Gb/s
3DMark’06 12211
Unigine Heaven 37,9 avg. FPS
1:10 hour HD video encoding 3:47 hours
400 FSB, 3.2GHz CPU:
Max temperature in linpack (OCCT) 87C (measured by Core Temp)
SiSoft Sandra Memory Throughput 6.45Gb/s
3DMark’06 14945
Unigine Heaven 38 avg. FPS
1:10 hour HD video encoding 2:59 hours
As you can see I have extreme temperatures in linpack, even though I have Thermaltake Big Typhoon VX cooler and efficient Arctic Cooling MX-2 thermal grease. However, you should understand that system never gets to these temperatures under standard system loads like gaming, video encoding, etc. Usually I get no more that 65-70 which is not that high.
Bare in mind that P5B Deluxe undervolt your CPU by 0.5V. It means when you set VCore to 1.525 it’s actually 1.475. Also when I set VCore higher than 5.125 (1.465 effective) motherboard automatically changes VCore voltage to Auto. In fact, it will work on set up voltage until you enter BIOS and save changes for the second time. In other words if you set voltage higher than 5.125 then you will need to set it again after you enter BIOS and change anything for the next time.
The main reason for me to OC my system was video encoding. Firstly I changed old 2 core E6300 to 4 core Q6600 and then OCed it. I used 1:10 hour HD video for testing purposes. Time has changed from 8:08 on stock E6400 to 3:47 on stock Q6600 and then to 2:59 on OCed Q6600. So performance increase is quite apparent and worth it for this class of tasks.
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