This page is for all of you PC geeks out there that are doing things like overclocking your|
celeron 300a processors.
Update: I now have a celeron 667 overclocked to 1GHz on the Aopen AX6BC...
Green text indicates new procedure changes or comments related to the 667.
Update: I now have a P3 1GHz overclocked to 1170MHz on the Aopen AX6BC...
Purple text indicates new procedure changes or comments related to the P3 1GHz.
Depending on the motherboard and when / where the 300a processor was made,
you may have to increase your cpu voltage to at least 2.2 volts. On some motherboards
(like the Abit BH6) you can increase the voltage in the BIOS. But what if you bought the
Aopen AX6BC? (Both are very good from what I have seen on the web.)
First of all, the default cpu voltage for the celeron 300a is 2.0 volts (1.65 for 667) (1.75 for 1GHz).
When the frequency is stepped up to 450/1000/1170 MHz then you may get problems booting
windows. Boosting the voltage allows the processor to have a cleaner signal (at least that is what I
heard). If you tape pins A119 A121 & B119 then you can fool the motherboard to provide 2.2 volts.
This all sounds good but what happends if one of the taped pins makes contact?
The following shows what happends when the tape (or nail polish) wears:
A119 contact then voltage goes to 2.6
B119 contact then voltage goes to 3.0
A119 and B119 contact then voltage goes to 3.4
Most people do not suggest going over 2.4 volts because you could fry the chip. Even some
think 2.4 is too high. So what do you do since over-clockable 300As are getting harder to find?
Forget about taping! If you are good with a soldering iron you can make your own adjustable voltage.
The following procedure was performed on an Aopen AX6BC but the idea is the same for all vcore
First of all...the disclaimer:
This procedure will void any motherboards warranty and you are doing the following at your own risk.
ID# 1 2 4 (8 not required for 300a) Usually 1 = red wire (8 required for celeron 667) 2 = yellow wire (8 required for Pentium 1GHz) 4 = blue wire B120 A120 A119 B119 8 = grey wire | | | | | | | | | | __|_____|_____|_____|_____|_____|_____|_____|_____|_____|__ | | | | | | | | | Aopen AX6BC voltage regulator chip | | | | | | | | | |___________________________________________________________| | | | | | | | | | | | | | | | | | | | | A121 (A121 wired to internal switch to ground for celeron 667) (A121 wired to internal switch to ground for Pentium 1GHz)
You're done (overclocked!!!).
The SCSI ids for the new celerons (vcore 1.65 volts or less) are a little more confusing
because voltages below 2.1 are stepped down by .05 volts. I know that you can buy a
slotket (FC-PGA to slot1 converter) now but I had previously cut the etches for the
voltages for the earlier 300a modification...Besides...You can still do this procedure
to the slotket without cutting etches (replace the voltage jumpers with SCSI id select
wires) and mount the SCSI id switch to the outside of the chassis.
The same applies to the Pentium Coppermine processors (vcore 1.75 or less).
This takes some time and patience but it is a nice efficient and easy way to change voltages.
By the way...If you did not buy your motherboard yet...there is a new version of the AX6BC
called the AX6BC Pro. This board has voltage stepping (in two .1 increments) in the BIOS.
With 1 AGP, 4 PCI, 1 ISA, 1 PCI/ISA there is alot of room for expansion.
This is what I have in my PC:
* * Normally powered off and used for software backup purposes.
The backup is performed using the linux command "dd" but that process is for another day.
Please feel free to email me if you have any comments about the vcore procedure or if you
want a SCSI id chart to select voltages from 1.3 to 3.5 volts.
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