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PCI Slots, any reason to use one instead of another?

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Anonymous
a b B Homebuilt system
February 4, 2005 12:13:34 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Lately I have heard discussion of which PCI slot to use for a new card. I
am just not familiar with this, I have always used whatever slot was
convenient, and honestly I have not had problems. Is there any general
rules to follow when installing new cards?

Somebody said not to use the slot right next to the AGP slot because it
shared an IRQ with the PCI slot and would not allow max performance.

Another person has said that the fastest cards should go to the bottom of
the board (furthest from the AGP) and from there on up each card should be
added in order of PCI performance needed.

Any truth to this?

Thanks,
--Dan

More about : pci slots reason

Anonymous
a b B Homebuilt system
February 4, 2005 12:13:35 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

dg wrote:

> Lately I have heard discussion of which PCI slot to use for a new card. I
> am just not familiar with this, I have always used whatever slot was
> convenient, and honestly I have not had problems. Is there any general
> rules to follow when installing new cards?
>
> Somebody said not to use the slot right next to the AGP slot because it
> shared an IRQ with the PCI slot and would not allow max performance.
>
> Another person has said that the fastest cards should go to the bottom of
> the board (furthest from the AGP) and from there on up each card should be
> added in order of PCI performance needed.
>
> Any truth to this?
>
> Thanks,
> --Dan

IIRC the AGP slot shares a bus with the PCI slot directly underneath it.
So I guess for gamers you want no possibility of "slowing down" the
feed to the video card. But I don't know what PCI cards people are
installing that require anywhere near the bandwidth of the GPU. TV
tuner maybe?
Anonymous
a b B Homebuilt system
February 4, 2005 3:24:12 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

"dg" <dan_gus@hotmail.com> wrote in message
news:2uwMd.260$ZZ.35@newssvr23.news.prodigy.net...
> Lately I have heard discussion of which PCI slot to use for a new card. I
> am just not familiar with this, I have always used whatever slot was
> convenient, and honestly I have not had problems. Is there any general
> rules to follow when installing new cards?
>
> Somebody said not to use the slot right next to the AGP slot because it
> shared an IRQ with the PCI slot and would not allow max performance.
>
> Another person has said that the fastest cards should go to the bottom of
> the board (furthest from the AGP) and from there on up each card should be
> added in order of PCI performance needed.
>
> Any truth to this?
>
> Thanks,
> --Dan
>
>

I always skip the PCI slot nearest the AGP slot in order to provide adequate
"breathing room" for the video card.

Matt
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Anonymous
a b B Homebuilt system
February 4, 2005 3:53:23 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

> Lately I have heard discussion of which PCI slot to use for a new card. I
> am just not familiar with this, I have always used whatever slot was
> convenient, and honestly I have not had problems. Is there any general
> rules to follow when installing new cards?

Use any slot, unless you find one that doesn't work -- then use
any other slot.
Anonymous
a b B Homebuilt system
February 4, 2005 5:26:51 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

dg wrote:

> Lately I have heard discussion of which PCI slot to use for a new card. I
> am just not familiar with this, I have always used whatever slot was
> convenient, and honestly I have not had problems. Is there any general
> rules to follow when installing new cards?
>
> Somebody said not to use the slot right next to the AGP slot because it
> shared an IRQ with the PCI slot and would not allow max performance.
>
> Another person has said that the fastest cards should go to the bottom of
> the board (furthest from the AGP) and from there on up each card should be
> added in order of PCI performance needed.
>
> Any truth to this?

Not to the last one. But the slot adjacent to the AGP card sharing IRQ with
it is correct.

That's not all the 'sharing' story though. PCI is a 4 slot standard so a
motherboard with, say, 5 slots will share IRQs between, usually, slots 4
and 5. And then, on board devices are essentially PCI cards without a
connector and share IRQs with SOME 'slot', which one depending on the
particular motherboard design.

You generally don't want I/O intensive devices sharing IRQs with each other
as that increases overhead with the system figuring out which card made the
request and a 'slot' can only do one thing at a time.

Sound cards can be particularly problematic, not because of I/O intensity
but, because of 'sound blaster' compatibility modes. The old sound blaster
was an ISA card and ISA can NOT share IRQs with anything, no way no how,
and that can create a situation where you have an IRQ incompatibility.
(which is where the biggest caveat about putting a card in the PCI slot
adjacent to AGP came from: a sound card. That will often royally mess
things up).

So, the biggest caveat is to avoid the PCI slot adjacent to AGP and if the
card is PCI compliant then the other slots should be okay since the
on-board devices should also be PCI compliant. The potential problem there
being putting an I/O intensive card (tuner) in a slot that's sharing with
an on-board intensive I/O device (LAN). But picking the 'end' slot and
'working up' won't necessarily solve that problem since you don't know
which slot is sharing with the on-board LAN.



>
> Thanks,
> --Dan
>
>
Anonymous
a b B Homebuilt system
February 4, 2005 7:47:56 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

"o-chan" <poda@REMOVEmac.com> wrote in message
news:ctulmt$59m8$1@netnews.upenn.edu...
> dg wrote:
>
>> Lately I have heard discussion of which PCI slot to use for a new card.
>> I am just not familiar with this, I have always used whatever slot was
>> convenient, and honestly I have not had problems. Is there any general
>> rules to follow when installing new cards?
>>
>> Somebody said not to use the slot right next to the AGP slot because it
>> shared an IRQ with the PCI slot and would not allow max performance.
>>
>> Another person has said that the fastest cards should go to the bottom of
>> the board (furthest from the AGP) and from there on up each card should
>> be added in order of PCI performance needed.
>>
>> Any truth to this?
>>
>> Thanks,
>> --Dan
>
> IIRC the AGP slot shares a bus with the PCI slot directly underneath it.
> So I guess for gamers you want no possibility of "slowing down" the feed
> to the video card. But I don't know what PCI cards people are installing
> that require anywhere near the bandwidth of the GPU. TV tuner maybe?

Yep, a TV tuner card sharing an IRQ with the video card will slow it down.
Happened to me...
!