ASUS  P/I-P55T2P4  Revision 3.x  FAQ

Hi I was never interested in publishing a homepage, because I had nothing to say to the world. I'm surfing around the web for over a year now and half a year ago I found my way to usenet. Some weeks ago I started posting in my favourite news group alt.comp.periphs.mainboard.asus  and because there are a lot of people with the same questions every day I thought it would be nice if I just could point them at a web side instead of repeating the same answers like a parrot. I asked how to get a free webpage and Lindsay Computer Systems owner Rick Lindsay offered me space on their website. So I grabed netscape Composer and here I go:

Please excuse my poor design and my poor English. I hope both will get better step after step.
Just after my second year at school my German teacher told me, that I have a lot of fantasy, most in spelling. :-)
But if you complain about my English wait for my French! :-)

First a few Warnings:

This is not an idiot proofed step by step 'how to build a computer' instruction for newbies!
It is more like a Datasheet where you can look up specific information if you know the basics!
If you don't know excactly what your are doing,  ask somebody with experience for advice!

You do everything at your own risk! I'm not responsible for any damages that may occur!
I will give my best to avoid any mistakes and misinformation, but I can't give you any warranty!

This page depends on my personal expirience with my Computer and from what I read in the web, so maybe something is different on your Computer!

Sorry, but this page deals only with Revision 3.xx Boards.
Previous Revisions don't support Split Voltage and higher bus speeds, so they are of no interest for me.

CPU                                        all Pentium and P-MMX , all AMD K5, all AMD K6 up to 233 (and more!) and IBM/Cyrix

Core Voltages                 any Voltage from 2.0Volt up to 3.3Volt

Frequency settings     Clock ratio from x1.5 up to x3.5   BUS frequency from 50MHz over 66MHz up to 83MHz

CACHE                               upgrade L2 cache from 256KB to 512KB  upgrade TAG RAM for full 512MB support
RAM                                       fully support two banks of Page Mode / EDO / Parity / ECC RAM up to 512MB


DISK                                      no UDMA a Problem?

ZIP                                           my ATAPI ZIP experiences

COOLING                       how to keep everything cool

USB                                        USB

Suspend Switch            My bad experiences with the suspend switch.

Noise Reduction          My way to get a silent system.

Over Clocking           A few words about o'c

Where to buy...              where can I get this tiny things I need?

Links                                       where to get more information.


All AMD K5 & K6 CPU's under 266MHZ require good cooling to run stably!

All K5 CPU's are supported.

All K6 CPU's up to 233MHz are fully supported.
If you use K6-233 first try to use it with 2.9V, because most of them will run fine. If they don't do, look at the core voltages part how to get 3.2V.
If you want to use the new K6-266 you had to test if your board and all components run stably at 75MHz or 83MHz before you buy it or you have to solder a BF2 jumper to your board! Look at core voltages how to get the needed 2.2V and look at higher multipliers how to add the BF2 jumper.
With added BF2 jumper the Board is supposed to support comming K6 3D and K6 3D+ too, because BIOS 205 added support for them! But thats (yet) not prooved!


All  clasic Pentium and all Pentium MMX are supported.


Because they have a bad marketing and give differnt Chips with different clock speeds the same Name I don't waste my time dealing with them. Sorry. :-(

Core Voltages
You can get every Voltage between 2.0V and 3.3V without soldering on your Mother Board!


This is the wiring schematic of my P55T2P4 Rev 3.0 Voltage jumper block.
(Thanks to Nicola Fabiano for the 29KOhm part)

        +-----> reference for output circuit
        +-----29KOhm-- <-- stabilized 3.3V source
2,5V    O O---85KOhm---Ground
2,7V    O O--130KOhm---Ground
2,8V    O O--180KOhm---Ground
2,9V    O O--210KOhm---Ground
res.    O O---85KOhm---Ground  (1MOhm for the latest 3.1 boards)

Vout= R/(R+29KOhm)*3.3V

ASUS used a lot of different resistors for the last jumper (called res. on my board) so it depends on your Board what voltage this gives.

measure the core Voltage

You can mesure the Core Voltage, without a CPU inside, but you must know wich of the hundred pins you must mesure and you have to short  the Vcore detection pin. Without a cpu and without the shortcut you will always measure the single voltage for an old Pentium without MMX and not the correct core Voltage for MMX CPU's!

But there is an easy way!
Measure the Core Voltage at the middle pin of the Single Power Plane jumper (JP 17  VRE/STD) against Ground with MMX CPU in socket. Please test this first with the standard jumper settings (2,5Volt, 2,7 Volt...etc) so you can be sure you measurements are correct!

higher Voltages

To get higher voltages you simply solder a resistor (¼ or ½ Watt) on a little connector and put it on the 2.9V jumper position.
(Don't change resistors on the MB like ASUS says! It's easy to destroy a MB!)

To get 3.0Volt you need a 100K Ohm resistor.
To get 3.1Volt you need a 270K Ohm resistor.
To get 3.2Volt you need a 820K Ohm resistor.
To get 3.3Volt you leave all jumper positions open.

lower Voltages

To get lower Voltages than 2.5V you had to set more than one jumper.
(Thanks to Fabian Robok who took these low voltage measurements.)

for 2.0V you had to set jumpers  2.5 & 2.7 & 2.8 & 2.9
for 2.1V you had to set jumpers  2.5 & 2.7 & 2.8
for 2.2V you had to set jumpers  2.5 & 2.7
for 2.3V you had to set jumpers  2.5     &       2.8
for 2.4V you had to set jumpers            2.7 & 2.8
for 2.5V you had to set jumpers  2.5

Of course the Values aren't exact the named voltages, but they are close to them.
( And don't expect with 2.5 jumper an exact voltage of 2.500000 Volt at the CPU ! )
There are some more combinations and you can use the 5th jumper too and you can adjust the voltage exact if you use a resistor instead of one jumper, but I see no reason for that.
extreme Voltages  EXPERTS ONLY!

Sure you can add a resistor from voltage reverence direct to ground (power LED Connector) to get lower than 2Volt or the resistor goes to 5V (power LED Connector) , that gives higher voltages than 3.3V.
But this is strictly reserved for experienced overclockers with electronic knowledge (and newbies who want to destroy their Board and CPU)!
I don't like this Idea, so I give no further advice!

Frequency settings

Bus Frequency

With the 4 official BUS frequencies (50, 55, 60 and 66MHz) all parts of the MB including PCI cards and ISA cards are running at their specifications.(and slower)
50 MHz     JP8 2-3    JP9 2-3    JP10 2-3
55 MHz     JP8 1-2    JP9 2-3    JP10 2-3
60 MHz     JP8 2-3    JP9 2-3    JP10 1-2
66 MHz     JP8 2-3    JP9 1-2    JP10 2-3

The remaining 4 frequencies exceed specifications for MB, PCI, ISA, Cache, CPU and Disk. So it depends on your whole system if they work or not.
68 MHz     JP8 1-2    JP9 1-2    JP10 1-2    Turbo Mode nearly no problems and nearly no speed increase.
75 MHz     JP8 1-2    JP9 2-3    JP10 1-2    Works on most machines. Probably you had to slow down RAM and Disk in BIOS.
83 MHz     JP8 1-2    JP9 1-2    JP10 2-3    Works on some machines with good components.
108 MHz   JP8 2-3    JP9 1-2    JP10 1-2    nobody ever claimed to have a running system with 108MHz (just a running PLL with freq counter attached)

If you don't know the basics for overclocking search for how to o'c on the net. (Or come back later)

CPU Multiplier

First a short introducion. When Intel designed their Pentium CPU's they decided to clock the CPU faster than the Rest of the Computer. So they build in a clock Generator in the CPU that runs faster than the BUS. This Clock generator runs at 1.5 x Bus Speed or at 2 x Bus speed. To select one of the multipliers they added a pin to the CPU called BF. The MB connects this pin to a jumper that alows to connect it to ground or not. So you can select between a P100 and a P133. When they made faster CPU's they added a second Pin, called it BF1 pin and renamed the BF pin to BF0. That alowes 4 possible clock ratios: x1.5 x2 x2.5 x3. When they designed the MMX version, they decided to replace the 1.5 ratio with the 3.5 ratio. Thats why the 233MMX is the fastest Intel socket 7 CPU. AMD copied this in their K6 (0.35µ). When AMD designed their new K6 (0.25µ) they decided to add a new BF2 pin instead of replacing the old ratios.

The advantage is, that overclockers can use higher bus speeds with lower multipliers.
The disadvantage is, that on old boards the BF2 pin is not connected and so no higher multiplier than 3.5 is possible.

On the T2P4 there are two jumpers to set the clock multiplier in the CPU.
That makes four combinations for clock multipliers.

              (BF1)           (BF0)
X 1.5    JP11 1-2   JP12 1-2   Pentium classic / K5 only!
X 2.0    JP11 2-3   JP12 1-2
X 2.5    JP11 2-3   JP12 2-3
X 3.0    JP11 1-2   JP12 2-3
X 3.5    JP11 1-2   JP12 1-2   Pentium MMX / K6 only!

YES you see right 1.5 = 3.5. It depends on the CPU what you get!
And Intel likes to disable higher multipliers in P166MMX and P200MMX. (officialy to prevent renaming, but unofficialy to prevent o'c)

higher Multipliers  EXPERTS ONLY!



Motherboards with only 256KB pipeline burst cache can be upgraded with a COAST Module.
I heard some complaints about generic COAST Modules.
I have zero problems with my ASUS CM1 REV 3.0 COAST Module. (even @83MHz zero problems)
It has 2 big and 2 smaller chips. The second smaller chip is the extended TAG RAM.
If your Module has only 2 big and one small chip you have no extended TAG RAM on it.


If you have more than 64MB of RAM in your Board you need an extended TAG RAM (or your machine will be s l o w)
Claims for performace loss vary from 5% to 40%.
My Opinion is: Everybody who spends much money on RAM and saves 2$ on the TAG RAM is dumb!

       If you have 256KB L2 Cache and no COAST Module you better get one quick!
       If you have a COAST Module check with a hardware detection Program the size of your TAG RAM.
         - If it says 8bit TAG RAM or 64MB cacheable area you have to add an extra TAG RAM for caching more than 64MB.
         - If it says 11bit TAG RAM or 512MB cacheable area you don't need an extra TAG RAM (its forbidden then)
       If you have 512KB L2 Cache on Board you need an extra TAG RAM for caching more than 64MB.

Go to your local electronics shop and buy a standard 32K X 8 15ns Static RAM and you will laugh about the price. (expect 2-6 US$)
Go to your local computer shop and buy a TAG RAM (exactly the same chip!) and your dealer will laugh, because a lot of money is changing hands. (My experience here in Germany)

Bios Auto settings for 70ns and 60ns RAM are lying! It always times memory correctly and not as it says, even at 83MHz.

I have not much to say about BIOS, because I never had any problems with it.
My advice: Don't flash if you have no problems. Flashing is risky. If it fails because of an error, black out etc your Computer won't boot again. You had to get a new BIOS Chip or search for somebody with a flash programmer, or do hot swapping (I don't like that idea!)
If you don't get the flashing success message try again and again with new or old BIOS, don't try to reboot!!!!!

If you flashed new BIOS enable Quick Power on Test.
Bios Auto settings for 70ns and 60ns RAM are lying! It always times memory correctly and not as it says, even at 83MHz.
enable VIRUS WARNING after you installed Operating System. It protects you from boot sector viruses.

The T2P4 has no UDMA mode. But every UDMA Drive will work well with the T2P4.
PIO MODE 4 is able to transfer 16MB/s (20MB/s @ 83MHz) and that is much more than the fastest IDE Drives in our days can deliver. Its the speed of getting the Data from the platters thats limits Disk acsess, not the interface! Even if you had to switch back to PIO MODE 3 when you are overclocking you won't see a difference with an average harddisk.
I use a 6.4GB IBM DHEA 36480 Deskstar 5 (one of the fastest UDMA Drives at beginning of 1998) and I'm happy about the performance increase after I replaced my old 1.6GB Western Digital Caviar 21600. Its compareable to my change from K5-100 to K6-200. Netscape starts in 4 seconds instead of 8 seconds for example
I use my Deskstar with BIOS set to PIO MODE 4 and WIN95 DMA checkbox enabled @ 83MHz and never had any problems. (CHIP Benchmark says 10MB/s 15% CPU load)
If you have OSR2 go to the Device Manger and enable the DMA Checkbox in your Drives property sheet. Don't try to instal Intel Bus Master Drivers if you have DMA Checkbox! WIN95 OSR2 Drivers are better and the Intel Drivers may be difficult to remove!

I use BIOS version 205 and never had any problems with my ATAPI ZIP. Its my master on second IDE chanel with CD ROM as slave. WIN 95 detects it automatically as drive F (my Disk is CDE). No problem with Drive letter B, because I have an old 5¼" Drive as B. If I say no second Flopy in BIOS, my ZIP Drive becomes Drive B in DOS without Drivers and stays Drive F in windows and no Drive B present. If I enable ZIP booting everything is the same, except I have a bootable Disk in my ZIP (normal format under WIN95 and sys b:) then ZIP becomes A and Floppy B.
So no problem at all with my ATAPI ZIP and BIOS 205. (I don't know about other BIOS Versions)

Always use a huge heatsink with quality ball beering fan for your CPU. Its an insurance for your investment.
And always use thermal compound between CPU and heatsink. If the heatsink has a rubber pad, remove it completly! Put a pea sized drop of thermal compound on the middle of the CPU. Then put the heatsink on the CPU with little pressure and move it round in smal circles until you have the feeling it fits perfect. Then fix it. (Forget about those heatsinks that are not fixed to the socket!)

If you like over clocking (or you want your PC last for ever) it may be a good idea to put little heatsinks on chipset, video card and other critical parts. Make the finger test to see wich chip will be happy about that. Use 'one second glue' (CYANACRYLAT) to fix them. You can equip every chip in your PC with a little heatsink for less than US$10. Go to your local electronics store to get them. Use a saw if they don't fit. Be sure they are not in the way of other components before you glue them, because removing may be impossible!

My solution for overall cooling is an inblowing fan at the bottom front of the case and the power supply blowing out. That will support the natural air stream of hot air. Be sure to have enough holes in your case to let enough air in.

This is the unverifyed copy of a message posted by timo

| RAM                   |
|                       |     _____/_____
| 12345  <-usb-connector|    /usb-cable /|
| 67890  <- 10-pins     |   /__________/ |   front-view
|                       |   |          | |
|                       |   |          | |
|                       |   |          | |
|                       |   |_1_2_3_4__| /
| PCI                   |   |__________|/
| PCI          CPU      |
| PCI                   |   1 black  ground
| ISA                   |   2 green  + data
| ISA                   |   3 white  - data
_________________________   4 red    + VCC

  red 1   + VCC
white 2   - Data               connector 1
green 3   + Data
black 4     Ground
      5   not connected
  red 6   + VCC
white 7   - Data               connector 2
green 8   + Data
black 9     Ground VCC
     10  not connected
Adding a 3A fuse into the 5Volt lines of both connectors, to prevent damage of the board in case of a shortcut may be a good idea!

Suspend Switch
I don't have a serious use for the suspend mode, but as you can imagine I just added a button to the SMI Lead because I like to add such little things. A year later I bought a K6-200, new RAM, my ATAPI ZIP and removed the SMI Button (because it was where the ZIP sits now). And I got a totaly stable System. Before that my system was somewhat unstable. Sometimes it runs for hours, then it closes some programs every few minutes because of protection errors. I thought It was the new RAM and CPU, but I was wrong! A few weeks later I added a new Suspend Button. And guess what --- an error every few minutes. Disconnected the Button from the MB and totaly stable system. I think the cable works as an antenna for some electric noise waves that causes the CPU to random crashes.
So if you have a Suspend Button and unexplainable crashes, try removing the cable from the MB!

Noise Reduction
If you like to have a silent system you had to detect the loudest noise sources. Disconnect the power from all fans and Disks and reconnect them step after step and listen. (disconnect CPU fan only a few seconds!)
If your CPU FAN is loud (most are little sirens) get a silent 40x40 or 60x60mm fan. Because they make much more airflow, you are able to put 3 diodes into the power line so the fan rotates a bit slower and makes much less noise, but better cooling than the old fan. Don't set the fan direct on the heatsink, let a gap of 5mm between them so it makes less noise. Use cardwork to direct the airflow and to fix the fan.
If your Disk is loud the easiest way is to get a new silent one. There are a lot of big, fast and silent Disks available today.
If you want to make an existing Disk silent you have to do a lot of work. Make a case (5¼"x2"x6") and fit it with carpet. Then add 0.7 KG of lead to every side of the Drive. Because if you don't do so and fix your Drive with rubber band everytime the head is moved the whole Disk will be pushed a little bit away. So the head will miss the expected track and had to moved back a bit. That will drasticaly increase seek time! Make sure there is at least 1cm space between Disk and case under, behind and over the drive and attach a silent fan to do proper cooling.
If your power supply is loud get a new silent one. If possible with temperatur regulation. But make a 'noise' test before you buy it.
For overall success fit the inner parts of your case with carpet, but be sure you don't reduce airflow, or your computer may soon be very silent.

Over Clocking
The P55T2P4 is a great board for overclocking. But o'c is not so easy as just putting a faster CPU in. It's a bit more tricky, but that's part of the fun!
The main issue is heat.
If you increase the clock speed of the CPU,  more heat is generated.
If you increase the voltage, the CPU reacts faster and so higher clock speeds are possible, but it gets hotter, too
But the hotter the CPU is, the slower it reacts, so less clock speed is possible.
So the two main things you need is good cooling and luck. :-)
Try to set the BUS Speed to 75MHz or 83MHz for best results.
I haven't proven it by my self but 208MHz, 225MHZ and 233MHz should give you nearly the same results when doing an overall benchmark. So it depends of your CPU, RAM, DISK, and all PCI/ISA Cards what setting is the best for your system.
My K6-200 works best at 2.5 x 83MHz and 2.7V and runs at 38 deg Celsius and begins crashing at 55C so there is a big security gap. (No crash at 65C with 2.8Volt)
3 x 75MHz needs 3.0V and runs at 45C and starts crashing at 54C. So in summer I will get problems.

If you use your Computer for business or other important stuff overclocking is a big NO NO!
Just saving "a few dollars" instead of buying a faster CPU or whole new system is not worth the risk of loosing your data!
40% of the companys that have had a serious crash and no Data Backup don't exist a jear after the crash!
Nothing can be destroyed by the o'c itself (except your data) but everything that gets to hot may be destroyed.

For more o'c advice search the web.

Where to buy...
In your local electronic shop you will get thermal grease, little heatsinks, conntectors, fans, resistors, TAG RAMS etc. Germany
So Sachen wie Jumper, Kabel, Stecker, Lüfter, Kühlkörper, IC's, MO-Disks, Transistoren, Wiederstände etc bekommt man sehr günstig bei Reichelt Elektronic. Ich habe vor über zehn Jahren zum ersten mal dort bestellt und habe es nie bereut. Die Waren waren immer preiswert, tadelos und sehr schnell geliefert. (Was die beiden großen Versender mit den bunten Katalogen (C & V) in Wochen brauchen braucht Reichelt in Tagen!) Normalerweise wenn man z.B Sonntags faxt sind die Sachen Dienstag oder Mitwoch da. Das web Angebot ist nicht so toll und die Katalog Angaben sind manchmal sehr spartanisch. Man muß halt gucken was man dort kauft und was vieleicht doch nicht. Aber für Kleinkram kenne ich keine bessere Quelle! (Mindestbestellwert nur 10DM, Porto & Verpackung 5.90DM)
Also Bastler am besten den kostenlosen Katalog bestellen und selber reinsehen. (Tel:04422 955-0 Fax:04422 955-111)

comming soon.

to be continued...


At last a repost of my Warnings:

This was not a idiot proofed step by step 'how to build a computer' instruction for newbies!
It was more like a Datasheet where you can look up specific information if you know the basics!
If you even yet don't know excactly what your are going to do,  ask somebody with experience for advice!

You will do everything at your own risk! I'm not responsible for any damages that may occur!
I gave my best to avoid any mistakes and misinformation.
Thanks to my BETA Testers : ABreimeris, Bob Faulkner, Fabian Robok, Jens Minnet, Norman S. Nadel, Hans-Martin Haga, Tillmann Steinbrecher for bug reports. (In order of their mails)

This page depends on my personal expirience with my Computer and from what I read in the web, so maybe something is different on your Computer!