ASUS P4P800 SE - PCI & IRQ's

krizrox · Post by **krizrox** » Wed Nov 10, 2004 6:01 pm

Had reason to upgrade my mobo recently to an ASUS P4P800SE. I was in a hurry and had to grab the first decent thing I could find.

I like the board except I'm having a bit of a hard time dealing with the PCI slots and IRQ settings. Wasn't an issue on my last ASUS board but this one....

Seems two PCI slots can't share the same IRQ setting. I've tried everything. BIOS seemingly allows you to assign the same IRQ to two different PCI slots but the POST screen always shows them as having different IRQs. And of course, WinXP shows the same.

Wondering if any fellow ASUS owners have seen the same thing? Or if there is a solution I'm not aware of.

Thanks!

valis · Post by **valis** » Wed Nov 10, 2004 10:15 pm

Winxp sp2, leave acpi enabled and disable HT.

no?

AndreD · Post by **AndreD** » Thu Nov 11, 2004 5:26 am

Use slot 1 and 5 for your cw cards..
Works fine even with HT here

Counterparts · Post by **Counterparts** » Thu Nov 11, 2004 5:36 am

Is your system (2K or XP?) installed in ACPI mode? If so, then "ACPI systems automatically configure all PCI devices."

If not (i.e. standard PC mode), then if you disable 'Plug & Play OS' in the BIOS and ensure that APIC is turned off (XP and more modern MOBOs I think) then you'll be able to set the IRQs in tne BIOS.

HTH,

Royston

krizrox · Post by **krizrox** » Thu Nov 11, 2004 10:12 am

Tried disabling APIC, PnP off, HT off, and still no go. The problem has nothing to do with WinXP (which is installed in Standard Mode). Appears to be a BIOS quirk. The POST screen that pops up after reboot, which details all the inner guts and settings, always shows two different IRQ values on my chosen PCI slots irregardless of how I have them set in BIOS. Well, actually one of the slots has the correct IRQ, the other always something else.

I haven't tried the slots 1/5 option though. Maybe will try that next. I see those slots are somehow tied together. Seems strange to put two Pulsar boards on opposite sides of the PCI buss but whatever works right? These are the only two PCI cards in the system so I guess there's little risk involved (latency or anything like that).

What seems strange to me is that my previous ASUS board allowed me to associate a single IRQ value to any two slots but this one doesn't.

<font size=-1>[ This Message was edited by: krizrox on 2004-11-11 10:14 ]</font>

Counterparts · Post by **Counterparts** » Thu Nov 11, 2004 10:16 am

krizrox wrote:

Tried disabling APIC, PnP off, HT off, and still no go.

The main thing's ACPI though...is your XP installed in 'Standard PC' mode? If not, then you're not going to be able to set the IRQs as far as I understand it. If it is in Standard PC mode, then something rather quirky's happening!

Royston

krizrox · Post by **krizrox** » Thu Nov 11, 2004 4:28 pm

Thanks guys for helping me resolve this. AndreD your suggestion was the winner. Installing the cards in slots 1 & 5 solved the problem. I saw that those two slots were connected but for some reason it never dawned on me to try them. I guess sometimes all it takes is a nudge to get the ol' brain working again.

Gracias!

valis · Post by **valis** » Thu Nov 11, 2004 6:10 pm

krizrox, I actually meant to ENABLE ACPI. Under XP (especially sp2) having ACPI enabled makes sharing irq's needless (provided you have the master board seen correctly in your cset.ini). The only downside here is that certain configurations seem to have issues with HT so for Creamware users its often better left off.

In any case glad it works...

Counterparts · Post by **Counterparts** » Fri Nov 12, 2004 3:58 am

krizrox wrote:
Installing the cards in slots 1 & 5 solved the problem.

That's just...weird!

Is that a MOBO-specific thing?

(I popped my 2x cards into the middle two slots!)

Royston

krizrox · Post by **krizrox** » Fri Nov 12, 2004 9:34 am

Well, I have Win XP installed in Standard Mode right now. I've actually flip-flopped back and forth between Standard and ACPI modes in the past. Not sure I ever saw any advantage one way or another in terms of performance. I turned HT back on just to see if that had any impact but I'm not noticing anything major in terms of performance. It doesn't seem to be hurting anything, that's for sure.

The main thing I wanted to avoid was the sharing of IRQ's with other mainboard features (like USB ports). I installed my two Pulsar boards in slots 1 & 5 and that seems to have solved all my problems so I guess it was something specific to this board.

Thanks again

Counterparts · Post by **Counterparts** » Fri Nov 12, 2004 10:15 am

Interesting stuff. My board's the P4PE (I think I got it based on a post Nestor made some time ago, as IIRC he recommended it quite highly).

Regarding the Standard vs. ACPI issue...I think that's more to do with Windows 2000, as it was for this OS that ACPI was first implemented and I have it on quite good authority that there exists in the source code comments from the original author to the tune of, "My God! It actually works!"

Royston

braincell · Post by **braincell** » Fri Nov 12, 2004 10:27 am

I have a an ASUS P4S8X. I'm using standard mode because it is the only way for XP to allow me to assign the IRQ settings in my bios. Their are 2 pairs of slots that each use the same IRQ.

vaporubs · Post by **vaporubs** » Sun Nov 28, 2004 7:55 pm

What is HT

On 2004-11-12 09:34, krizrox wrote:
Well, I have Win XP installed in Standard Mode right now. I've actually flip-flopped back and forth between Standard and ACPI modes in the past. Not sure I ever saw any advantage one way or another in terms of performance. I turned HT back on just to see if that had any impact but I'm not noticing anything major in terms of performance. It doesn't seem to be hurting anything, that's for sure.

The main thing I wanted to avoid was the sharing of IRQ's with other mainboard features (like USB ports). I installed my two Pulsar boards in slots 1 & 5 and that seems to have solved all my problems so I guess it was something specific to this board.

Thanks again

Post by **hubird** » Sun Nov 28, 2004 8:27 pm

Hyper Threading.
It is Something Terrible

About 80% says turn it off, you won't loose much performance and it's much safer to do that

my pc friends can explain it in detail, but it's also widely discussed in different forums, if you need to know what's all about, there is lots of good information available