Does IRQ sharing eat performance?

[sMashPiranha]

In particular, my AGP Video card and my ATA-100 card which is running both of my hard drives are sharing IRQ 11. Is this likely to hurt the performance of my drives/video? How can I change them? In the screen just after the POST it says something like
RAID Controller IRQ 11
AGP VGA IRQ 11
So I can't just change it in windows right? this would be a BIOS thing? Also the IDE card is in the first PCI slot, if I move it it randomly decides to not recognise anything on the secondary IDE port.

 

[corkyg]

My experience is that AGB video cards and SCSI cards require dedicated IRQs with no sharing. Do a complete story of your PCI slots to determine which share with which. That varies by mobo and BIOS.

We can now just about eliminate the use of parallel ports and at least one serial port, and that frees up 2 IRQs. The trick is to get a BIOS that will let you assign those to other uses. AMI in most cases does not. Phoenix does in some cases. MR BIOS used to be great for that . . . but . . . that's yesterday's news.

The PCI slot that shares with the AGP slot should not be used unless it can be manually divorced.

 

[TunaBoo]

IRQ sharing ideally would not impact preformance.

However, all devices don't agree with the ideal world concept.

 

[Jiggz]

As long as IRQ sharing is done only on IRQ Steering and holders, you should be OK.

 

[JackMDS]

IRQ sharing by it nature must reduce performance ( it have to alternate between the components if they act at the same time). The question is How Much?

In most cases, it is negligible.

As said before, more important is what shares with what.

Modern fast Video Cards do not like to share, usually the AGP slot, and the first PCI slot share IRQ, by leaving the PCI slot that is next to the AGP open you will avoid Video Card IRQ sharing.