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What Mainboard for minimal Shared IRQ - PCI slots

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February 20, 2003 8:48:44 AM

Hi,

today most manufacturers fix there onboard components to the PCI slots to share the IRQ with that PCI slot.
Well sharing is no problem for most components, but for there are still problems here.
I have ABIT KT7a Mainboard, where the onboard is share with PCI4 and I can safly use that slot for my SBLive.
PCI2 and 3 get Network adapters and have both no sharing
and PCI1 is share with AGP and SCSI and Grafik have no shareing problems too.

No I want to buy a new mainboard and don't know wich I could use. I tried ASROCK K7VT2 but it was useless to me four USB controllers all on a different PCI slot, so all have shareing. And the onboard lan had no OS/2 driver :-(

Are there any sugestions? Why does the Tom's Hardware comparison not include such information about wich PCI slot and components have to share? (mostly it's easy to figure that out, mine even shows this in it'S bios-setup).

I am happy about every mainboard inforamtion concerning shared slots.

Ciao/2 Christoph


<P ID="edit"><FONT SIZE=-1><EM>Edited by Birdy27 on 02/20/03 05:52 AM.</EM></FONT></P>
March 11, 2003 11:47:58 AM

2 questions...

1. is the ASRock K7VT2 any good for a running a couple of months till I can decide on a top spec board to get ie stable, good performance

2. are you getting the IRQ-PCI info from device manager ???


Hmmm, wonder if I can get a valid page fault ???
these invalid ones are far too commonplace...
March 11, 2003 1:22:20 PM

Just get a board with the minium stuff that you need. You can easily just turn off the stuff you don't need like USB/serial/RAID or whatever.
Tom's hardware probabaly doesn't include such information in its reviews because it is largely irrelevant. Most modern products support IRQ sharing without any problems, for example I have 3 devices sharing IRQ17. Btw what items do you have that don't support IRQ sharing? Your network cards? Because there are always some slots with unique IRQs just like you have now.

<A HREF="http://www.anandtech.com/myanandtech.html?member=114979" target="_new">My PCs</A> :cool:
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March 11, 2003 3:30:42 PM

IRQ sharing is not the problem it once was.

First, the hardware is uniquely identified at an electronics level so that only one device comes live at at time. Were it otherwise you'd get some total strangeness like dancing patterns on your monitor when your speakers make sound or wild noises from your speakers when the network is going, etc.

Second, most modern software (especially Win2k and XP) doesn't actually use IRQs for device access. Instead a software contrivance called a "miniport" is used. Miniports uniquely identify each component/board by a Buss and Device ID number, rather than an IRQ. Feed the Buss and Device ID to a register on the southbridge and the device you want pops up. Even devices apparently on the same IRQ are still uniquely identified by this method. In fact, Win2k and XP actually put all devices on the same IRQ, letting the miniports sort it out. The IRQs you see in device manager are "virtual" devices, provided only for compatibility with older software.

Finally, there is next to no performance hit for doing this. Since even though you can trace an on-board device's PC board foil right to a PCI socket, the device is still uniquely identified by hardware and thus can be accessed by software at full speed. There is no turning one device off to get at the other.



--->It ain't better if it don't work<---
March 11, 2003 3:54:42 PM

Nicely explained, Teq.

---There may be more than one way to do it, but why would anyone want to remove the fur from a feline?---
March 11, 2003 4:02:40 PM

:smile: My Pleasure.

--->It ain't better if it don't work<---
March 11, 2003 4:12:14 PM

Yes I have IRQ shareing problems with network cards.
And I had to figure out there are not always unique IRQ slots. The ASRock has none and the one my father has has one.
Would need too.

What I wonder about is, that I disable all onboard components that share IRQ with slot and still only the one slot worked with Networkcards ?!?
March 11, 2003 4:15:47 PM

Thanx for the answer.

May be it's because I still use Win98. Because Win98 drivers of Realtek still have IRQ shareing problems :-(

At my fathers they just wont work.
With ASRock where both cards had shared IRQ Win98 won't even start :-(

When I got you right this is a problem of the win98 driver model and the realtek driver?
March 11, 2003 4:18:42 PM

Jut for notice there is no device manager in the ASRock bios.
The ASRock Bios has none features. Just set harddiscs and bootorder. You feel like having a notebook.

To make things worse all slots share with one of the USB controllers, wich you can't turn off.

But you can see the IRQs after startup iin the overview
March 11, 2003 4:21:46 PM

Win9x is pretty much outmoded software these days. Board design has moved beyond the old ISA model into something permitting far more I/O than was possible with 16 IRQs. Win2k and Winxp have kept pace with these changes.

Sounds like it's time for an OS upgrade...



--->It ain't better if it don't work<---
March 11, 2003 4:23:42 PM

I think the "Device Manager" was a reference to your Operating System.

Right click "My Computer" then click Properties, you will find device manager tucked away on one of the tabs.



--->It ain't better if it don't work<---
!