Upgrading and Overclocking the old Asus P2B Slot 1 Motherboard

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Part One: Upgrading

The Asus P2B is one of the most popular 440BX based Slot 1 motherboards around. Originally the P2B was designed to be used with the Slot 1 Intel PII and early PIII Katmai CPUs. Although the newer revisions do support Slot 1 Coppermines PIII, there is still no Vcore adjustments and therefore overclocking is limited. With some understanding and a few tricks, almost all revisions of the Asus P2B can be upgraded to Coppermine CPU and successfully overclocked too.

There are many revision of the Asus P2B. If you don’t know what revision your Asus P2B is, you can look between the 1st and 2nd ISA slots – the revision number is stamped in that area. Officially according to Asus, only rev. 1.12 and later and some rev. 1.10 support the Coppermine CPU. That’s due to the Vcore regulator in the older P2B which only goes down to 1.8 volts while the Coppermines need 1.6 volts. If you just plug a Coppermine Slot 1 PIII in the older rev. P2B motherboard, it will not boot and you’re running the risk of damaging the CPU.

The remedy for these limitations is to abandon the Slot 1 CPU all together and use a FC-PGA (flip-chip) Coppermine CPU with a Slot 1 to FC-PGA adapter card (slocket). The Coppermine CPU can be either a Pentium III or a Celeron II. Here are the steps to upgrade the Asus P2B motherboard:

  1. Flush the P2B motherboard to the latest Bios 1012. The new bios not only fixed many bugs but also contains the necessary codes that needed to run the Coppermine CPU. The latest Bios and the flushing utility is available to download from Asus Website at www.asus.com.tw
  2. Choose a slocket that supports Coppermines. There had been reports of good results with Asus S370-133, Asus S370-L and MSI MS6905 Master slocket. Stay away from any Abit slockets and Iwill slockets can be troublesome sometime.

  3. Install the FC-PGA Coppermine CPU carefully and set the Vcore voltage jumpers to 1.8V for the earlier P2B and 1.6V for the later P2B. The motherboard will boot at this setting and you could increase the voltage later on for farther overclocking.

By switching to a FC-PGA Coppermine CPU and flushing the Bios, the older rev. Asus P2B motherboards gain the ability to run faster CPUs together with the later rev. P2Bs. Both also add the capability to have Vcore voltage adjustment, which is essential for overclocking.

Tong Yan



Part Two: Overclocking

In part one, I went over how to upgrade the 440BX based Asus P2B Slot 1 motherboard to faster Coppermine CPUs by flushing the Bios and using a slotket. In Part II I will go over on how to overclock this motherboard.

The P2B is actually a very stable overclocker because of its quality and the 4:1 PCI divider. Even at 133 MHz front bus speeds and above, the 4:1 divider keeps your PCI peripherals well within the PCI spec. In the earlier P2B, FSBs are limited above 100 MHz to only 103, 112 & 133. The later P2B has more FSB selections.

On the earlier P2B, the on board external clock multiplier can only be set to 8X at its highest but it doesn’t matter anymore when using it with a Coppermine CPU. The P2B motherboard will run with whatever numbers the Coppermine CPU has in its locked on-chip clock multiplier, although sometimes this will cause a false report of the CPU speed during boot. If you run any kind of benchmark utility on it, you will know all your numbers are still there. All overclocking on the Asus P2B is done on the front bus speed only with Vcore voltage adjustments.

There’s no Vcore voltage adjustment on the P2B motherboard, but it can be done on the Slotket. The voltage regulator on the P2B doesn’t like 0.05V +/- adjustments such as 1.75V or 1.85V. Instead, the Vcore voltage should be rounded up to the next number like 1.8V or 1.9V.

There are also some issues with the Slotket: Make sure to check your case’s inside clearance before buying one. Some cases that have a power supply right next to the CPU Slot, such as the InWin A500, may have clearance problems with some taller slotkets like the Asus S370-133.

Also, many slotkets have a jumper to select between Coppermine and Celeron CPUs. This Celeron setting is referring to the original .25 Celeron, not the current .18 Celeron II. If you’re using a Celeron II CPU, the jumper should be set on the Coppermine setting.

If you don’t have a copy of the P2B User manual, you could download one from the Asus Website’s manual download page). Asus’ own PC Probe motherboard monitoring software utility is also available on their website.

Here’s my setup and let the overclocking begin!

  • Asus P2B rev. 1.02 motherboard with Bios 1012
  • Intel Celeron II 633 mhz FCPGA, SL3W9, Malay, week 33
  • Stock retail Intel heatsink & fan combo and aluminum water-block with 55 watt peltier
  • Asus S370-133 and Asus S370-L slotket
  • 512 mb of PC100 Toshiba (256mb), PNY (128mb) and Hitachi (128mb) SDRAM running at Cas 2
  • ELSA Gloria II 64mb AGP Professional 3D graphic card
  • Initio 9200 dual channel UW SCSI + Intel NIC
  • 2X Fujitsu SCSI MAG3182LP 18.2gig 10k HDD
  • IBM GXP22 IDE 13.5gig 7200rpm & WD IDE 6.4gig 5400rpm HDD
  • External SCSI Zip100
  • SoundBlaster 16 + Roland Midi
  • Motorola 56k ISA hardware modem

The Celeron II 633 MHz has a rather high 9.5X multiplier with 66mhz stock FSB and 1.65 volt Vcore. In the 1st attempt, I set the FSB to 112 MHz and Vcore to 1.8 volts on the slocket. The aluminum water-block with 55 watt peltier was installed on the CPU with Arctic Silver thermal compound.

The Result: 1063 MHz and Stable! That’s 68% overclocking!

Not bad at all for a two and half year old motherboard. Unfortunately, I do not have any instruments to measure temperatures. I tried again with 133mhz FSB but the computer didn’t boot at all.

Back at 1063 MHz, the system didn’t crash after 22 hours of 3D animation rendering in 3D Studio Max. Next in line was running SPECviewperf 6.1.2., a professional OpenGL 3D graphic benchmark, for 3 times completely. The scores were very close to the scores of IBM and HP graphic workstations (equipped with the same ELSA Gloria II graphic card) on SPECviewperf 6.1.2’s website.

However, those graphic workstations have a PIII 850 CPU. The overclocked Celeron 633’s performance is actually correct. Typically overclocked Celeron II is about as fast as a Pentium III that’s 200-250 mhz slower.

Next, I removed the water-block and the water-cooling system. I then installed the retail Intel heatsink and fan combo that comes with the Celeron 633 and re-applied the Arctic Silver thermal compound. At 1063mhz and 1.8V Vcore, the Celeron produces around 30 watts of heat.

That proved to be too much for the stock heatsink to handle. I lowered the speed to 978 MHz and it became stable, but it’s still a little too hot according to the tip of my finger. The system runs perfectly at 950 MHz with the stock Intel heatsink. I did some more testing at that speed.

One of them is “backing up” the Entrapment DVD into a Divx;-) movie by using FlaskMPEG. With the Divx;-) Low-Motion video codec decoding on Bilinear Filtering and Mp3 audio codec at 128 kb/s, it took five and half hours to convert the whole two hours DVD into an AVI movie file that could fits onto a CDR.

So folks, don’t just throw away your old Asus P2B Slot 1 motherboard yet. With some upgrading and some overclocking, there is still a lot of useful life left in it.

Tong Yan



Since my article of “Upgrading and Overclocking the old Asus P2B Slot 1 Motherboard” published couple months ago, I have been flooded with emails asking more questions and comments. This follow up article is my attempt to respond to those questions and comments in regarding to upgrading the P2B motherboard.

My article only covers the original pain P2B (no extension) models. However, many of the emails are questions about other P2B models. Since the P2B was so popular, Asus made 10 other improved models in addition to the original; here are the all the P2B versions:

  • P2B
  • P2B-B (Baby AT format)
  • P2B-F (5 PCI slots)
  • P2B-L (onboard Ethernet)
  • P2B-S (onboard SCSI)
  • P2B-LS (onboard Ethernet and SCSI)
  • P2B-N (NLX format, onboard Audio and Ethernet)
  • P2B-VM (Micro ATX format and optional onboard audio)
  • P2B-D (Dual CPU)
  • P2B-DS (Dual CPU, onboard SCSI)
  • P2B-D2 (Dual CPU, onboard SCSI, Ethernet and VGA)

In addition, Asus also made a variation of the P2B with onboard Firewire/IEEE-1394 interface for the original Sony Vivo Desktops.

With all the email questions I received, I decided to do more research on this topic. I had found the best place to find more upgrading info regarding to different models of the Asus P2B is on CtechNet.com’s Asus Motherboard Page. The best place to ask more questions about the P2B is on Asus motherboard Newsgroup (alt.comp.periphs.mainboard.asus).

Besides the email questions, other emails are thank yous and upgrading results. Most of the upgrades for the P2B rev. 1.02 are successful. One of readers even overclocked his PIII 700E to 933 with 133 MHz FSB. However, the same guy tried it with his other P2B (rev.1.04) without success. He mentioned it might have something to do with the VIO jumper on this version.

There’s even one adventurous reader who tried a 133 MHz “EB” version of the PIII on a P2B motherboard. No matter what he tried, the motherboard just refused to power up. So folks, only 100 MHz FSB Coppermine CPUs can be use with the P2B.

One reader with a P2B-LS rev.1.03 had problems with the onboard SCSI at first, but it was fixed after flashing the latest BIOS. To my surprise, one guy took my advice and upgraded the CPU to a Celeron 600, overclocking it to 900 MHz – this on his Asus P2-99B rev. 1.02 motherboard; this board uses the Intel 440LX chipsets.

Many readers asked me for a processor recommendation. Unless you’re planning to do high-end 3D designs or databases, the Celeron 600 and 633 are the best deal. Just about all the reports, including mine, has shown that these 2 Celerons overclock to 900 and 950 easily. Celerons with speeds higher than 633 usually don’t overclock very well due to their high multipliers.

While many P2B owner upgraded their motherboard successfully, some were not so lucky. Just keep in mind that if my advice doesn’t work, it’s time to get a new motherboard for your computer.

Tong Yan


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