- Feb 3, 2007
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Explanation of BIOS Options & Recommended Overclocking Settings :
Note: These settings are very smiler/ same on all Gigabyte Motherboards. This could apply to other motherboards too.
R.G.B.: Helps to enhance the performance of the GPU and
VRAM. "Auto" allow the BIOS to automatically set the R.G.B. mode based on system configurations. This Option must be set to "Auto" for successful overclock.
CPU Clock Ratio: This is the CPU Multiplier. The lowest it can reach is 6x (most of the time) and the highest is dependent on the CPU. I recommend that you set this to the highest possible due to the fact that it puts fewer limits on the FSB (i.e. Less likely to hit an FSB wall etc.). But, there are cases in which it should or could be lowered.
CPU Host Clock Control: This option is "Disabled" by default. You MUST change this to "Enabled" in order to overclock the CPU.
CPU Host Frequency (Mhz): This is the FSB. Increase this value by 50-70Mhz over your Stock FSB during your first attempt.
For an 800 MHz FSB this is set to 200 MHz.
For a 1066 MHz FSB this is set to 266 MHz.
For a 1333 MHz FSB this is set to 333 MHz.
You can also enter any other value like 300 (1300FSB).
Change this item to reach the desired speed. This multiplied by the CPU multiplier gives the clock speed. I recommend that you change this by 50-100Mhz during the first few test phases to narrow down the stable overclock. Then after you reach the Maximum Clock speed (the point at which Prime95 fail in less than 5 hours) decrease the FSB by 20-50Mhz or increase the CPU core voltage .
CPU Frequency: This is the speed after any changes in the FSB and/or Multiplier.
This is equal to:
[fixed]
Multiplier * FSB = CPU Frequency (CPU Speed)
Example:
10*300=3000Mhz
[/fixed]
PCI Express Frequency (Mhz): This is the PCIe frequency for the PCIe slots. Keep this at 100Mhz or "Auto" .
C.I.A.2: CPU Intelligent Accelerator 2 (C.I.A.2) is a system designed to automatically adjust the CPU Clock speed by a given percentage. This option is "Disabled" by default. It must be set to "Disabled" in order to successfully overclock the CPU .
Performance Enhance : Must be set to "Disabled" for a successful overclock.
System Memory Multiplier (SPD): This is the RAM SPD. Change this item so that the "Memory Frequency" shown below the SPD is not exceeded. It is OK to be under the "Memory Frequency" shown.
Memory Frequency (Mhz): The first RAM value listed (I will call this the "Rated RAM Speed" to make life easier) (to the left ) is the normal speed of the RAM being used; the second (to the right) is the memory frequency that is automatically adjusted according to the "CPU Host Frequency (Mhz)" and "System Memory Multiplier" settings. I would strongly suggest you decrease the SPD to stay at or below the "Rated RAM Speed". If your RAM is overclockable (i.e. RAM like the Crucial Ballastix) you should still set the SPD to the "Rated RAM Speed" as it would be one less variable in a CPU overclocking failure until you find the best stable overclock. I recommend that you DO NOT overclock the RAM until you reach a stable CPU speed.
System Voltage Control: Determines whether to manually set the system voltages (i.e. CPU core voltage, RAM voltage, PCIe voltage, etc). "Auto" lets BIOS automatically set the system voltages as required. I recommend that you set this to "Auto" only if your overclock is small like 10-11%. Set this to "Disable" if your overclock is high (i.e. 400+Mhz CPU speed increase). Also set this to "Disable" if you need to change RAM voltages, this is specially true for most high performance RAM like the Crucial Ballastix and Corsair XMS2, etc. If your RAM is higher than 1.8v you must set this to "Disabled" .
DDR2 OverVoltage Control: This is the RAM voltage. Increase this by +0.1v increments to reach the voltage specified by the ram manufacture. The standard voltage is 1.8v. So if your voltage is rated as 2.2v increase this to +0.4v since 1.8 + 0.4 = 2.2.
[fixed]
Rated RAM voltage - 1.8 = The needed voltage increase
Example:
2.2 -1.8 = 0.4
[/fixed]
PCI-E OverVoltage Control: Allows you to set PCIe voltage. There should be no need to change this value for 98% of the overclockers.
FSB OverVoltage Control: Allows you to increase the FSB voltage. Increase this to reach stability under high FSB (i.e. 310Mhz+).
(G)MCH OverVoltage Control: This is the Northbridge voltage. Most overclockers will not need to change this setting. Change this to increase stability under certain FSBs (i.e. 420Mhz+). Note that an increase in this setting WILL produce increase motherboard heat output. A Northbridge cooler is recommended for most P35/X38 motherboards even if you are not changing the MCH voltage. Gigabyte motherboards with out Ultra Cool should have a small Northbridge fan ( I noticed a 8C drop in my motherboard temperatures once I installed a 40mm fan on the heat sink on my P35-DS3L.).
CPU Voltage Control: Allows you to set the CPU voltage. Increase the voltage little by little until you reach stability at a given CPU speed*. Increasing this setting WILL cause an increase in CPU temperatures, so therefore a good CPU cooler is highly recommended. You should also monitor your temperatures through software like CoreTemp. DO NOT LET CPU TEMPERATURES EXCEED 65C. If your temperatures exceed 65C you are still safe but long term operation will not be advisable. You should NEVER let the CPU reach thermal threshold (Tjunction). This is the point where the CPU automatically decreases the Multiplier to 6x, even if SpeedStep is disabled.
* Some users have reported that decreasing the CPU voltage will allow an increase in the overclock/stability. This is due to the fact that less voltage means less heat therefore more stable overclock. This is mainly true for most of the E6xxx CPU (not the 6x50s, most of the time).
Normal CPU Vcore This is the standard CPU voltage at stock settings.
Note: Will include a picture of the BIOS settings soon.
Note: These settings are very smiler/ same on all Gigabyte Motherboards. This could apply to other motherboards too.
R.G.B.: Helps to enhance the performance of the GPU and
VRAM. "Auto" allow the BIOS to automatically set the R.G.B. mode based on system configurations. This Option must be set to "Auto" for successful overclock.
CPU Clock Ratio: This is the CPU Multiplier. The lowest it can reach is 6x (most of the time) and the highest is dependent on the CPU. I recommend that you set this to the highest possible due to the fact that it puts fewer limits on the FSB (i.e. Less likely to hit an FSB wall etc.). But, there are cases in which it should or could be lowered.
CPU Host Clock Control: This option is "Disabled" by default. You MUST change this to "Enabled" in order to overclock the CPU.
CPU Host Frequency (Mhz): This is the FSB. Increase this value by 50-70Mhz over your Stock FSB during your first attempt.
For an 800 MHz FSB this is set to 200 MHz.
For a 1066 MHz FSB this is set to 266 MHz.
For a 1333 MHz FSB this is set to 333 MHz.
You can also enter any other value like 300 (1300FSB).
Change this item to reach the desired speed. This multiplied by the CPU multiplier gives the clock speed. I recommend that you change this by 50-100Mhz during the first few test phases to narrow down the stable overclock. Then after you reach the Maximum Clock speed (the point at which Prime95 fail in less than 5 hours) decrease the FSB by 20-50Mhz or increase the CPU core voltage .
CPU Frequency: This is the speed after any changes in the FSB and/or Multiplier.
This is equal to:
[fixed]
Multiplier * FSB = CPU Frequency (CPU Speed)
Example:
10*300=3000Mhz
[/fixed]
PCI Express Frequency (Mhz): This is the PCIe frequency for the PCIe slots. Keep this at 100Mhz or "Auto" .
C.I.A.2: CPU Intelligent Accelerator 2 (C.I.A.2) is a system designed to automatically adjust the CPU Clock speed by a given percentage. This option is "Disabled" by default. It must be set to "Disabled" in order to successfully overclock the CPU .
Performance Enhance : Must be set to "Disabled" for a successful overclock.
System Memory Multiplier (SPD): This is the RAM SPD. Change this item so that the "Memory Frequency" shown below the SPD is not exceeded. It is OK to be under the "Memory Frequency" shown.
Memory Frequency (Mhz): The first RAM value listed (I will call this the "Rated RAM Speed" to make life easier) (to the left ) is the normal speed of the RAM being used; the second (to the right) is the memory frequency that is automatically adjusted according to the "CPU Host Frequency (Mhz)" and "System Memory Multiplier" settings. I would strongly suggest you decrease the SPD to stay at or below the "Rated RAM Speed". If your RAM is overclockable (i.e. RAM like the Crucial Ballastix) you should still set the SPD to the "Rated RAM Speed" as it would be one less variable in a CPU overclocking failure until you find the best stable overclock. I recommend that you DO NOT overclock the RAM until you reach a stable CPU speed.
System Voltage Control: Determines whether to manually set the system voltages (i.e. CPU core voltage, RAM voltage, PCIe voltage, etc). "Auto" lets BIOS automatically set the system voltages as required. I recommend that you set this to "Auto" only if your overclock is small like 10-11%. Set this to "Disable" if your overclock is high (i.e. 400+Mhz CPU speed increase). Also set this to "Disable" if you need to change RAM voltages, this is specially true for most high performance RAM like the Crucial Ballastix and Corsair XMS2, etc. If your RAM is higher than 1.8v you must set this to "Disabled" .
DDR2 OverVoltage Control: This is the RAM voltage. Increase this by +0.1v increments to reach the voltage specified by the ram manufacture. The standard voltage is 1.8v. So if your voltage is rated as 2.2v increase this to +0.4v since 1.8 + 0.4 = 2.2.
[fixed]
Rated RAM voltage - 1.8 = The needed voltage increase
Example:
2.2 -1.8 = 0.4
[/fixed]
PCI-E OverVoltage Control: Allows you to set PCIe voltage. There should be no need to change this value for 98% of the overclockers.
FSB OverVoltage Control: Allows you to increase the FSB voltage. Increase this to reach stability under high FSB (i.e. 310Mhz+).
(G)MCH OverVoltage Control: This is the Northbridge voltage. Most overclockers will not need to change this setting. Change this to increase stability under certain FSBs (i.e. 420Mhz+). Note that an increase in this setting WILL produce increase motherboard heat output. A Northbridge cooler is recommended for most P35/X38 motherboards even if you are not changing the MCH voltage. Gigabyte motherboards with out Ultra Cool should have a small Northbridge fan ( I noticed a 8C drop in my motherboard temperatures once I installed a 40mm fan on the heat sink on my P35-DS3L.).
CPU Voltage Control: Allows you to set the CPU voltage. Increase the voltage little by little until you reach stability at a given CPU speed*. Increasing this setting WILL cause an increase in CPU temperatures, so therefore a good CPU cooler is highly recommended. You should also monitor your temperatures through software like CoreTemp. DO NOT LET CPU TEMPERATURES EXCEED 65C. If your temperatures exceed 65C you are still safe but long term operation will not be advisable. You should NEVER let the CPU reach thermal threshold (Tjunction). This is the point where the CPU automatically decreases the Multiplier to 6x, even if SpeedStep is disabled.
* Some users have reported that decreasing the CPU voltage will allow an increase in the overclock/stability. This is due to the fact that less voltage means less heat therefore more stable overclock. This is mainly true for most of the E6xxx CPU (not the 6x50s, most of the time).
Normal CPU Vcore This is the standard CPU voltage at stock settings.
Note: Will include a picture of the BIOS settings soon.
very good and easy to read guide 
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