Hi BJ64,
My rig happens to be the same as yours (A64 3200+ Winchester, AX8, Corsair Value Select PC3200 2 x 512MB). So my settings of overclocking (to 2.20 GHz, 2.40 GHz, 2.66 GHz) may be helpful. (Maximum stable CPU frequency in my system seems to be somewhere between 2.66 GHz and 2.70 GHz.) First, you should change External Clock and Voltages settings NOT in BIOS but in ?ABIT OC Guru? within Windows until you fully understand what is going on and to what extent your system can tolerate. Otherwise you have to clear CMOS each time the system crashes! Second, value RAM should not be a bottleneck of overclocking or performance in real-world applications as discussed in
Official 939 Memory Matrix. However, since maximum stable frequency of this value RAM is around 220 MHz, you need to use memory divider in BIOS. For more details of overclocking A64, please read
Quick and dirty A64 clocking guide. Once you learn the basic, you will be able to enjoy various settings with confidence. If you find your favorite setting, you may change External Clock and Voltages settings in ?uGuru Utility? in BIOS.
In case you have changed the BIOS settings, please
clear CMOS and restore the default before proceeding. Then enter the BIOS Setup, select ?Power Management Setup?, and
disable ?Cool?n?Quiet Technology? (just to make the CPU multiplier transparent). Boot into Windows and run ?ABIT OC Guru?. Pull down ?OC Guru Setting? subscreen and make sure that the ?Default? button is selected. Click the ?Configure Preset? button. In ?Configure Preset? dialog box, select User1, User2, User3 respectively from the dropdown menu and enter the following values:
User1 Ext Clock: 220, PCIE Clock: 100, VCore: 1.5000, VDDR: 2.90, VNB: 1.60, VSB: 2.60, VHT: 1.30, VDDRRef: Omv, CPU FanEQ: Normal
User2 Ext Clock: 240, PCIE Clock: 100, VCore: 1.5250, VDDR: 2.60, VNB: 1.65, VSB: 2.65, VHT: 1.35, VDDRRef: Omv, CPU FanEQ: Cool
User3 Ext Clock: 266, PCIE Clock: 100, VCore: 1.5500, VDDR: 2.60, VNB: 1.65, VSB: 2.65, VHT: 1.35, VDDRRef: Omv, CPU FanEQ: Cool
User1, User2, and User3 are intended to overclock CPU to 2.20 GHz, 2.40 GHz, 2.66 GHz respectively. Now you have to change ?DRAM Clock? and ?LDT Bus Frequency? in BIOS. These settings depend on the intended CPU frequency.
Overclocking to 2.20 GHz (External Clock: 220 MHz, CPU multiplier: x 10, DRAM Clock: DDR400 = 220 MHz, LDT Bus Frequency: FSB x 5 = 1100 MHz). Enter the BIOS Setup and select ?Advanced Chipset Features?. Select ?DRAM Configuration?. Select ?DRAM Timing Selectable? and select ?By SPD? and accept. Select ?DRAM Timing Selectable? again and select
Manual and accept. Then select ?DRAM Clock? and select
DDR400. The actual memory frequency will be 220 MHz = PC3520 (400 : 400 = 1 : 1 = 220 : 220). This is the reason for raising VDDR to 2.90 V. Select ?DRAM Command Rate? and select
1T. Exit. Next select ?LDT & PCI Bus Control?. Select ?LDT Bus Frequency? and choose
FSB x 5. The HT bus frequency will be 220 MHz x 5 = 1100 MHz. This is higher than the spec. frequency of 1 GHz, but the system should be stable. Save and exit the BIOS Setup. Now boot into Windows. Run ?ABIT OC Guru?, pull down ?OC Guru Setting? and press the User1 button. Run
CPU-Z and make sure that CPU Frequency is 2200 MHz and Memory Frequency is 220 MHz. Run
SuperPi (1M) and make a quick stability test.
Dictionary: External Clock = FSB (Front Side Bus) (frequency). HT (HyperTransport) = LDT (Lightning Data Transfer).
Overclocking to 2.40 GHz (External Clock: 240 MHz, CPU multiplier: x 10, DRAM Clock: DDR333 = 200 MHz, LDT Bus Frequency: FSB x 4 = 960 MHz). Enter the BIOS Setup and this time change ?DRAM Clock? to
DDR333. The actual memory frequency will be 200 MHz = PC3200 (400 : 333 = 6 : 5 = 240 : 200), so that the memory is completely stable. Then change ?LDT Bus Frequency? to
FSB x 4. The HT bus frequency will be 240 MHz x 4 = 960 MHz. Boot into Windows and press the User2 button in ?ABIT OC Guru?. Run CPU-Z and make sure that CPU Frequency is 2400 MHz and Memory Frequency is 200 MHz. Run SuperPi and make a quick stability test.
Overclocking to 2.66 GHz (External Clock: 266 MHz, CPU multiplier: x 10, DRAM Clock: DDR266 = 177 MHz, LDT Bus Frequency: FSB x 4 = 1064 MHz). Enter the BIOS Setup and change ?DRAM Clock? to
DDR266. The actual memory frequency will be 177 MHz = PC2832 (400 : 266 = 3 : 2 = 266 : 177). (The memory in my system is unstable at DDR333 = 222 MHz@2.90 V. Even if it were stable, the difference of real-world performance between DDR266 and DDR333 would be negligible.) ?LDT Bus Frequency? should remain
FSB x 4. The HT bus frequency will be 266 MHz x 4 = 1064 MHz. Boot into Windows and press the User3 button in ?ABIT OC Guru?. Run CPU-Z and make sure that CPU Frequency is 2660 MHz and Memory Frequency is 177 MHz. Run SuperPi 32M. Your score will be 30+/-5 min (if your OS is WINXP; WIN2K is tad slow in this application, about x 1.2). Compare it in
SuperPi Contest!
At this frequency and voltage, my CPU temperature rises up to 65 Celsius degree at full load with the stock heat sink and fan. As this is well below the critical temperature of 90 degree, I am not too much worried about cooling.
BTW,
Cool?n?Quiet may be enabled or disabled in the BIOS Setup, that does not affect overclocking; it just adjusts the CPU multiplier according to the CPU load. For example, if it is enabled and Ext Clock is set to 266 MHz, then the CPU frequency will be 266 MHz x 5 = 1330 MHz at idle or normal load, and 266 MHz x 10 = 2660 MHz at full load. The memory frequency is proportional to Ext Clock, so remains 177 MHz.