Fix for the Asus Ipanel and PCI/AGP card conflicts.


This is my fix for a problem I had when fitting one of Asus's Ipanel displays connected to my Asus A7M/266 socket A motherboard.

The fix also works on the Asus CUSL2 series of boards. 

The problem may well occur on any Asus boards that support the Ipanel as it's a design fault in the Ipanel.

Fixes boot time bios conflicts with

  • Nvidia chipset video cards 
  • Promise IDE and Promise Raid controllers 
  • Adapter Scsi cards
  • 3Com 905b's network cards.
  • Many other PCI cards.

Please note, Asus have now modified the Ipanel to fix this problem, on Ipanels from PCB 1.02 with PCBA B14, These appear to be the new plastic cased Ipanels.

If you have one of these Ipanels you do not need to do the Reset modification mentioned below but may still need to do the anti stutter mod on the other page.

More details on Asus's mod  here.

I fitted an Ipanel to my new Asus A7M/266 motherboard and my problems started.

The Ipanel appeared to conflict with the bios initialization on my Creative GeForce 2 GTS video card, I only got video 1 boot in 20, the other 19 times all I got was video card fail beeps.
And if I replaced it with an ATI card the video worked but my Promise Raid controller bios was only seen 1 time in 20 boots.
If it got past the boot then everything seems to work perfectly.
With the Ipanel disconnected everything worked quite happily every boot so it was definatly the Ipanel causing the problem.

A bit of research on the net lead me to http://www.cusl2.com/ (now http://www.asusboards.com/) where they have a forum devoted to the Ipanel, mainly on it's use on the Cusl2 of course.
It appeared the Ipanel often caused the same problems on that motherboard as well.
Conflicts with Promise IDE and Adapted Scsi cards causing the cards bios not to be seen at boot time or the card not to initalise correctly.
So I decided to do some basic checking, first thing was to try a Rev 1.02 Ipanel instead of the 1.01 but that had the same problems.
After looking at the pinout in Ipanel manual I noticed the PCIRST# which I guess is the reset signal from the PCI bus also going to the Ipanel to reset that at boot time.
I had one of those feelings (you know the ones, you can't say why but it just seems right), cut the connection to the PCIRST# pin on the Ipanel and fitted a 1K resistor in series.

And it worked.........,no more problems at boot with either the Promise raid controller or the GeForce.
My theory is that the Ipanel is putting too much load on the PCIRST line and due to the usual electric tolerances some PCI cards are more sensitive to this than others and weren't resetting properly.
Inserting the resistor reduces the load on the PCI bus but still passes the signal to the Ipanel.

Removing the resistor temporarily confirmed the problems returned and it wasn't something else I'd accidentally done.

Update: It's since been discovered (somebody in the CUSL2 forum spotted it) that there is a 0.1uf capacitor (see picture below) in the Ipanel connected between the PCIRST signal and Gnd, this must be greatly increasing the rise and fall time of the reset signal and is almost certainly why the PCI cards are getting upset.

Some people have just been cutting the capacitor leg rather than fit the resistor, cutting the cap will stop the reset problems but may cause another problem with the Ipanel. The cap looks like it was added at a late stage as the PCB isn't labeled for it so it may have been fitted to fix a different problem and Asus didn't sufficiently test that mod.

See below for exact details of the mod

There is a second problem with the Ipanel.

When the Ipanel updates, either when you press the button, or on the CUSL2 when the display auto updates about every 30 seconds, you get a noticeable pause in what ever is running.

This is most noticeable in games or playing MP3's.

More details of this problem here www.jimhearne.co.uk/ipanel/stuttermod.htm 

Feel free to post a link to this page or copy the details but please give me credit for working it out if you post the details somewhere else.

www.jimhearne.co.uk/ipanel

Email: Please do not email me with Questions about the Ipanel anymore, it's been removed from my pc and consigned to the junk cupboard.

At work we are no longer using Asus boards so i don't know about compatibility with newer boards though all indications from mail i've been sent are that all newer boards still suffer from the stuttering.

 

 

The Reset mod

Please note, try this at your own risk.

  • You need a soldering iron and a 1K resistor, any wattage.

  • Cut the wire in the ribbon cable going to pin 19 of the 24 way connector.
    (It's the 6th conductor in from the unmarked side of the cable)
    If you look in the Ipanel manual (page 8 here) it's labeled as PCIRST#
  • Join the 2 cut ends with the 1K resistor.
  • Insulate the joints and power up, that's it.

 

  

The pictures above were taken of my first version of the mod, as I wasn't sure it was going to work I removed the top of the IDC connector and fitted a short piece of wire into the connector from the other side.