- Joined
- Jul 15, 2008
Everything you want to know about overclocking with a Gigabyte P45 motherboard
Here's my attempt to give back to the community. I learned a lot here for my first OC and didn't even need to ask anything. Help me compile as much info as we can here.
I'm new to overclocking so I'm both learning what options are available and how this Award BIOS presents them compared to AMI (or whatever Asus boards use). Please chime in when you see something missing or incorrect. I appreciate all the input I can get!
My system:
Motherboard: Gigabyte EP45-DS3R, F8a BIOS
CPU: Intel Core 2 Q9450
Memory: Mushkin Ascent PC2-8500, 2x2GB
rest in my sig...
Last update: July 30, 2008, 8:55 PM
I'll cite settings for 3 clock speeds, when the settings differ:
1) 8x 440 = 3.52 GHz, prime stable for 9d18h45m
2) 8x 485 = 3.88 GHz, unlikely to be stable, but I'm getting close, 25 mins so far
3) 8x 500 = 4.0 GHz, my personal best, completely unstable, prime95 causes an instant BSOD
All these BIOS settings are in M.I.T. - Motherboard Intelligent Tweaker.
CPU Clock Ratio:
Stock: 8x (for the Q9450)
Mine: 8x
This multiplied by your clock speed gives your final cpu clock. Range is 6-8 for the Q9450. Mine is 8x... isn't everyone's q9450 at 8x?
Clock Chip Control
>>> Standard Clock Control
CPU Host Frequency (FSB clock):
Stock: 333MHz (for the Q9450)
Mine(1): 440MHz
Mine(2): 485MHz
Mine(3): 500MHz
No explanation necessary, is there? Push her as high as you can, especially if you only have an 8x multiplier.
>>> Advanced Clock Control
CPU Clock skew:
Stock: 0ps
Mine(1,2,3): 150ps
This and MCH clock skew are like voodoo. The benefits are clear but the only way to find out if it helps is trial & error. I lucked out and found that 100ps CPU skew & 250ps MCH skew let me boot at FSB clock speeds I couldn't even POST at, such as 475MHz. At lower clocks they help stabilize things too. I can get higher clocks with all stock voltage. Then with some trial & error going for 500 I found 150 was a bit better. Make sure you read MCH skew for more info (next, just keep reading).
MCH Clock skew:
Stock: 0ps
Mine(1,2,3): 250ps
See CPU Clock skew above for basics. The trick to tuning these is that they go together, so you should make a grid with timings your board allows and then start trying random combos till something helps at frequencies you can't even POST at. Then when you hit something keep tuning them trying all the near combos. Tedious, but essential.
DRAM Performance Control
Performance Enhance:
Stock: Turbo
Mine: Standard
I don't know what this changes, haven't bothered testing it.
(G)MCH Frequency Latch:
Stock: Auto
Mine(1,2,3): 333MHz
This would be your FSB strap in Asus/AMI lingo. At low fsb speeds I can set this to 400 or 333, but at higher speeds I have to keep it at 333 and keep a 1:1 ratio (see below).
System Memory Multiplier:
Stock: Auto
Mine(1): 2.40B
Mine(2,3): 2.00B
I believe Asus boards call this the divider. This changes your FSB strap according to the letter suffix. To run my memory & cpu in sync I have to keep this at 2.00x, and specifically 2.00B at higher clocks. The letter suffix is explained in the BIOS.
At 5:6, 1056MHz, latch is 333MHz (2.40B).
memory clock = latch * FSB = 2.4 * 440 = 1056MHz
multiplier (or divider) = FSB / RAM = 440 / 528 = 5/6
DRAM Timing Selectable:
Stock: Auto
Mine: Manual
I have these at 5-5-5-15, I'm leaving the fine-tuning till I find my max stable speed.
Advanced Timing Control
Not yet.... There will be more here later, as the timing options are rather cryptic and warrant explanations & comparisons to Asus/AMI terminology. I only know what a few of them really do so far.
Voltage
CPU Vcore:
Stock: 1.25v
Mine(1): 1.35v
Mine(2): 1.45v
Mine(3): 1.475v
Voltage to your cpu, but we all knew that one. Defaults to ~ 1.25v for 45nm cpus. Max. recommended by Intel is 1.38v for the Q9450, I have seen people report going as high as 1.5v for suicide runs. My board has a vdrop of ~ 0.05 above 1.3, and ~ 0.01-0.02 below 1.25 or so. vdroop is 0.05-0.07.
I don't want to be the one to find out that 1.45v (CPU-Z reading, idle) kills your CPU in 3 months, so even if I stabilize 4GHz I don't know if I'll run that high normally. 1.4 already sounds high to me, so that's my absolute limit for every day operation (for now anyway! )
1.35 BIOS results in 1.248 load and 1.312 idle.
CPU Termination:
Stock: 1.2v
Mine(1): 1.24v
Mine(2): 1.32v
Mine(3): 1.34v
This is known as CPU VTT on Asus boards. Turning this up helped at high frequencies but I found that after setting the clock skews I could turn this down to the stock setting and still get >400 mhz. I read that this is key to OCing quads, so I'll experiment with it when I try to break 450.
CPU PLL:
Stock: 1.5v
Mine(1): 1.57v
Mine(2): 1.61v
Mine(3): 1.61v
When increasing vcore + other settings I increase this too. I am uncertain of what it does, and I have seen recommendations that this stay below 1.55v. This board goes in weird increments, 1.5 -> 1.57 -> 1.59 -> 1.61.
CPU Reference:
Stock: 0.76v
Mine: 0.76v
I gather that reference voltages are used to determine whether a signal is high/low. At higher voltages it may be wise to increase this slightly, but I haven't touched it yet. I believe I read that this should be 65-70% of vcore.
MCH Core:
Stock: 1.1v
Mine(1): 1.2v
Mine(2): 1.34v
Mine(3): 1.36v
Voltage to your NB (north bridge). MCH stands for Memory Controller Hub. I don't think I could go past 1.4. It might be safe but I haven't any info on how much it can take.
MCH reference:
Stock: 0.9v
Mine: 0.9v
The same as the other ref. voltages but for your NB.
MCH DRAM/reference:
Stock: 0.76v
Mine: 0.76v
See other reference voltages above.
ICH I/O:
Stock: 1.5v
Mine: 1.5v
Voltage for your SB (south bridge). ICH stands for I/O Controller Hub.
DRAM Voltage:
Stock: 2.0-2.1v
Mine: 2.06v
Another no brainer, volts to your memory. Oddly most boards give your memory a bit more than you specify here. I get 2.06-2.08.
DRAM Termination
Stock: 0.9v
Mine: 0.9v
This is the voltage that terminates signals to your memory.
Channel A/B Reference:
Stock: 0.9v
Mine: 0.9v
The same as CPU reference but for memory.
If you want me to list a BIOS setting I skipped over just let me know.
Here's my attempt to give back to the community. I learned a lot here for my first OC and didn't even need to ask anything. Help me compile as much info as we can here.
I'm new to overclocking so I'm both learning what options are available and how this Award BIOS presents them compared to AMI (or whatever Asus boards use). Please chime in when you see something missing or incorrect. I appreciate all the input I can get!
My system:
Motherboard: Gigabyte EP45-DS3R, F8a BIOS
CPU: Intel Core 2 Q9450
Memory: Mushkin Ascent PC2-8500, 2x2GB
rest in my sig...
Last update: July 30, 2008, 8:55 PM
I'll cite settings for 3 clock speeds, when the settings differ:
1) 8x 440 = 3.52 GHz, prime stable for 9d18h45m
2) 8x 485 = 3.88 GHz, unlikely to be stable, but I'm getting close, 25 mins so far
3) 8x 500 = 4.0 GHz, my personal best, completely unstable, prime95 causes an instant BSOD
All these BIOS settings are in M.I.T. - Motherboard Intelligent Tweaker.
CPU Clock Ratio:
Stock: 8x (for the Q9450)
Mine: 8x
This multiplied by your clock speed gives your final cpu clock. Range is 6-8 for the Q9450. Mine is 8x... isn't everyone's q9450 at 8x?
Clock Chip Control
>>> Standard Clock Control
CPU Host Frequency (FSB clock):
Stock: 333MHz (for the Q9450)
Mine(1): 440MHz
Mine(2): 485MHz
Mine(3): 500MHz
No explanation necessary, is there? Push her as high as you can, especially if you only have an 8x multiplier.
>>> Advanced Clock Control
CPU Clock skew:
Stock: 0ps
Mine(1,2,3): 150ps
This and MCH clock skew are like voodoo. The benefits are clear but the only way to find out if it helps is trial & error. I lucked out and found that 100ps CPU skew & 250ps MCH skew let me boot at FSB clock speeds I couldn't even POST at, such as 475MHz. At lower clocks they help stabilize things too. I can get higher clocks with all stock voltage. Then with some trial & error going for 500 I found 150 was a bit better. Make sure you read MCH skew for more info (next, just keep reading).
MCH Clock skew:
Stock: 0ps
Mine(1,2,3): 250ps
See CPU Clock skew above for basics. The trick to tuning these is that they go together, so you should make a grid with timings your board allows and then start trying random combos till something helps at frequencies you can't even POST at. Then when you hit something keep tuning them trying all the near combos. Tedious, but essential.
DRAM Performance Control
Performance Enhance:
Stock: Turbo
Mine: Standard
I don't know what this changes, haven't bothered testing it.
(G)MCH Frequency Latch:
Stock: Auto
Mine(1,2,3): 333MHz
This would be your FSB strap in Asus/AMI lingo. At low fsb speeds I can set this to 400 or 333, but at higher speeds I have to keep it at 333 and keep a 1:1 ratio (see below).
System Memory Multiplier:
Stock: Auto
Mine(1): 2.40B
Mine(2,3): 2.00B
I believe Asus boards call this the divider. This changes your FSB strap according to the letter suffix. To run my memory & cpu in sync I have to keep this at 2.00x, and specifically 2.00B at higher clocks. The letter suffix is explained in the BIOS.
At 5:6, 1056MHz, latch is 333MHz (2.40B).
memory clock = latch * FSB = 2.4 * 440 = 1056MHz
multiplier (or divider) = FSB / RAM = 440 / 528 = 5/6
DRAM Timing Selectable:
Stock: Auto
Mine: Manual
I have these at 5-5-5-15, I'm leaving the fine-tuning till I find my max stable speed.
Advanced Timing Control
Not yet.... There will be more here later, as the timing options are rather cryptic and warrant explanations & comparisons to Asus/AMI terminology. I only know what a few of them really do so far.
Voltage
CPU Vcore:
Stock: 1.25v
Mine(1): 1.35v
Mine(2): 1.45v
Mine(3): 1.475v
Voltage to your cpu, but we all knew that one. Defaults to ~ 1.25v for 45nm cpus. Max. recommended by Intel is 1.38v for the Q9450, I have seen people report going as high as 1.5v for suicide runs. My board has a vdrop of ~ 0.05 above 1.3, and ~ 0.01-0.02 below 1.25 or so. vdroop is 0.05-0.07.
I don't want to be the one to find out that 1.45v (CPU-Z reading, idle) kills your CPU in 3 months, so even if I stabilize 4GHz I don't know if I'll run that high normally. 1.4 already sounds high to me, so that's my absolute limit for every day operation (for now anyway! )
1.35 BIOS results in 1.248 load and 1.312 idle.
CPU Termination:
Stock: 1.2v
Mine(1): 1.24v
Mine(2): 1.32v
Mine(3): 1.34v
This is known as CPU VTT on Asus boards. Turning this up helped at high frequencies but I found that after setting the clock skews I could turn this down to the stock setting and still get >400 mhz. I read that this is key to OCing quads, so I'll experiment with it when I try to break 450.
CPU PLL:
Stock: 1.5v
Mine(1): 1.57v
Mine(2): 1.61v
Mine(3): 1.61v
When increasing vcore + other settings I increase this too. I am uncertain of what it does, and I have seen recommendations that this stay below 1.55v. This board goes in weird increments, 1.5 -> 1.57 -> 1.59 -> 1.61.
CPU Reference:
Stock: 0.76v
Mine: 0.76v
I gather that reference voltages are used to determine whether a signal is high/low. At higher voltages it may be wise to increase this slightly, but I haven't touched it yet. I believe I read that this should be 65-70% of vcore.
MCH Core:
Stock: 1.1v
Mine(1): 1.2v
Mine(2): 1.34v
Mine(3): 1.36v
Voltage to your NB (north bridge). MCH stands for Memory Controller Hub. I don't think I could go past 1.4. It might be safe but I haven't any info on how much it can take.
MCH reference:
Stock: 0.9v
Mine: 0.9v
The same as the other ref. voltages but for your NB.
MCH DRAM/reference:
Stock: 0.76v
Mine: 0.76v
See other reference voltages above.
ICH I/O:
Stock: 1.5v
Mine: 1.5v
Voltage for your SB (south bridge). ICH stands for I/O Controller Hub.
DRAM Voltage:
Stock: 2.0-2.1v
Mine: 2.06v
Another no brainer, volts to your memory. Oddly most boards give your memory a bit more than you specify here. I get 2.06-2.08.
DRAM Termination
Stock: 0.9v
Mine: 0.9v
This is the voltage that terminates signals to your memory.
Channel A/B Reference:
Stock: 0.9v
Mine: 0.9v
The same as CPU reference but for memory.
If you want me to list a BIOS setting I skipped over just let me know.
Last edited: