IRQ Sharing?

BEn_2600+ · 23 Nov 2006 at 18:01

If some devices on my computer are sharing IRQ's would this lower performance? For example my X1800XT is sharing an IRQ (16) with 6 devices including the card itself. Is this wrong or is there nothing to worry about?

Thanks in advance, Ben

Darg · 23 Nov 2006 at 18:16

On a high end motherboard it shouldn't cause a problem but it's always best to avoid IRQ sharing.

Worst cases are when the Graphics card and Sound card are sharing the same IRQ channel. For example with my cheap Asrock board when they were both on IRQ 16 I had a lot of problems as soon as I got into games. When I changed the Sound card PCI slot so it used IRQ 17 then it worked without much problems.

If possible move PCI devices around so that they don't use IRQ 16. What are the other 6 devices that use the channel?

BEn_2600+ · 23 Nov 2006 at 18:22

Intel ICH8 PCI Express root port 1
Intel ICH8 PCI Express root port 5
Intel ICH8 USB Universal host controller
Intel P965 PCI Express root port
Marvell Yukon PCI Express gigabit ethernet controller
Radeon X1800XT

All using IRQ 16, will this reduce the performance of my graphics card or is it nothing to worry about?

Thanks, Ben

Darg · 23 Nov 2006 at 19:17

Ah it seems to just be mainly PCI-E ports which are actually to do with your graphics card anyway. You also have a USB controller and your Ethernet controller using the same IRQ. Odd that they designed the motherboard that way but they must have known that it wouldn't have an issue with it.

You can rest assured that there won't be any serious conflicts between those devices. Unless you happen to be playing Oblivion while transferring 1GB of data a second through the ethernet while simutaneously copying data at 100mb/s from a few different usb devices. :rolleyes:

BEn_2600+ · 23 Nov 2006 at 19:28

Darg said:
You can rest assured that there won't be any serious conflicts between those devices. Unless you happen to be playing Oblivion while transferring 1GB of data a second through the ethernet while simutaneously copying data at 100mb/s from a few different usb devices.

Lol, Ok thanks a lot, but what about internet gaming, because im connected to my router via ethernet when im online playing say, BF2 wont performance be worse because im using the gfx card and ethernet at the same time, whilst their sharing IRQ's.

Thanks, Ben

Tom|Nbk · 23 Nov 2006 at 19:34

sorry to hijack your thread ben, just wondered how my irq stuff stands so far ive had absoloutly zero problems just thought id check up as my systems packed to the brim atm,

I/O Port 0x00000000-0x00000CF7 PCI bus
I/O Port 0x00000000-0x00000CF7 Direct memory access controller

I/O Port 0x000003C0-0x000003DF Intel(R) P965/G965 PCI Express Root Port - 29A1
I/O Port 0x000003C0-0x000003DF Radeon X1900 CrossFire Edition

IRQ 23 Intel(R) ICH8 Family USB Universal Host Controller - 2830
IRQ 23 Intel(R) ICH8 Family USB2 Enhanced Host Controller - 2836
IRQ 23 Creative SB Audigy 4 (WDM)

IRQ 9 Microsoft ACPI-Compliant System
IRQ 9 SCSI/RAID Host Controller
IRQ 9 SCSI/RAID Host Controller

IRQ 16 Intel(R) P965/G965 PCI Express Root Port - 29A1
IRQ 16 Radeon X1900 CrossFire Edition
IRQ 16 Intel(R) ICH8 Family USB Universal Host Controller - 2834
IRQ 16 Intel(R) ICH8 Family PCI Express Root Port 1 - 283F
IRQ 16 Radeon X1900 Series
IRQ 16 Intel(R) ICH8 Family PCI Express Root Port 5 - 2847
IRQ 16 Standard Dual Channel PCI IDE Controller

IRQ 17 Intel(R) ICH8 Family USB Universal Host Controller - 2835
IRQ 17 Intel(R) ICH8 Family PCI Express Root Port 6 - 2849
IRQ 17 Marvell Yukon 88E8056 PCI-E Gigabit Ethernet Controller

IRQ 18 Intel(R) ICH8 Family USB2 Enhanced Host Controller - 283A
IRQ 18 Intel(R) ICH8 Family USB Universal Host Controller - 2832

IRQ 19 Intel(R) ICH8 Family USB Universal Host Controller - 2831
IRQ 19 Marvell Yukon 88E8001/8003/8010 PCI Gigabit Ethernet Controller
IRQ 19 Intel(R) 82801HR/HH/HO SATA AHCI Controller

Memory Address 0xA0000-0xBFFFF PCI bus
Memory Address 0xA0000-0xBFFFF Intel(R) P965/G965 PCI Express Root Port - 29A1
Memory Address 0xA0000-0xBFFFF Radeon X1900 CrossFire Edition

I/O Port 0x000003B0-0x000003BB Intel(R) P965/G965 PCI Express Root Port - 29A1
I/O Port 0x000003B0-0x000003BB Radeon X1900 CrossFire Edition

BEn_2600+ · 23 Nov 2006 at 19:49

No problem mate, yours seems similar with your Gfx sharing irq's with USB and other PCI-E devices, what motherboard have you got by the way?

Ben

Tom|Nbk · 23 Nov 2006 at 19:49

BEn_2600+ said:
No problem mate, yours seems similar with your Gfx sharing irq's with USB and other PCI-E devices, what motherboard have you got by the way?

Ben

P5B Deluxe

BEn_2600+ · 23 Nov 2006 at 20:50

Same chipset as mine aswell it must be how the chipset/boards are designed that the PCI-E and USB share IRQ's

LoadsaMoney · 23 Nov 2006 at 20:53

Same here on a Gigabyte DS4.

IRQ 16 Intel(R) P965/G965 PCI Express Root Port - 29A1 OK
IRQ 16 Radeon X1800 Series OK
IRQ 16 Intel(R) ICH8 Family USB Universal Host Controller - 2834 OK
IRQ 16 Intel(R) ICH8 Family PCI Express Root Port 1 - 283F OK
IRQ 16 Intel(R) ICH8 Family PCI Express Root Port 5 - 2847 OK
IRQ 16 Marvell Yukon 88E8053 PCI-E Gigabit Ethernet Controller OK

Tom|Nbk · 23 Nov 2006 at 21:00

BEn_2600+ said:
Same chipset as mine aswell it must be how the chipset/boards are designed that the PCI-E and USB share IRQ's

yup thats exactly it.