Which PCIe 16x Slot?

iMogal · 11-09-2007, 11:15 AM

Hey guys

Does it matter what 16x PCIe slot you plug a single graphics card into?
Say on the P5K Prem, can a single Gfx card be plugged into the lower slot?
or does it have to be the upper one?

My reasonning is because of my case. (Silverstone LC16M)
If I can slide the vid card into the lower 16x PCIe slot, I can get an 8800
series into my case. In the upper slot, it wont fit, its too long.
Other wise, I'm kinda stuck with a physically smaller (8600 series) card.

iMogal · 11-10-2007, 12:53 AM

No one?

Can someone try for me and see?

zapionics<alt> · 11-10-2007, 01:55 AM

It shouldnt make any difference which slot you use so long as they are both 16x.

Having said that, sometimes the motherboard manufacturers do silly things, so it may be worthwhile to try both and do a bench (3dmark) and see if there is any difference.

traveler · 11-10-2007, 03:10 AM

Check the manual and make sure that both slots are true 16 slots and don't just look like 16 slots.

shaihulud · 11-10-2007, 07:26 AM

Always check the manual to confirm the routing and electrical specifications of the slot. PCIe is often quoted as it will work and route to but this is not always true. This is especially important if integral PCIe peripherals are using the lanes that would be allocated to the slot. You may note in the manual that particular slots only can support so many lanes or electrical. Just another caveat, some lanes have a different mapping to memory, and some have to go thru other buses.

iMogal · 11-10-2007, 09:54 AM

The manual doesn't say anything about single card use.
The board does have 2 PCIe x16 ports.
When setting up a xfire thou, the say to use the primary PCIe port for the master gfx card...
So other then that... ? uhm....

*SRTDodge05* · 11-10-2007, 10:03 AM

2 x PCI Express x16
(blue x16 mode, black x4 or x1 mode)

shaihulud · 11-10-2007, 12:42 PM

The P35 has 16 PCIe lanes for PEG only. The ICH9 has 6 PCIe lanes that are routable. Your mother board has an extra 16x SIZE slot, but not the lanes to accommodate 16x speed. Page 2-20 and 2-21 of your manual go into the details you need for your motherboard.

Note that if 4 lanes are used for the secondary adaptor, then there are only 2 lanes left which can be used in the slots above the primary graphics slot. If you do not use the secondary graphics adaptor you can use a PCIe peripheral in the secondary slot up to 4 lanes and still have 2 lanes left for the upper slots. This is for your motherboard.

*SRTDodge05* · 11-10-2007, 12:44 PM

Quote:

Originally Posted by shaihulud

The P35 has 16 PCIe lanes for PEG only. The ICH9 has 6 PCIe lanes that are routable. Your mother board has an extra 16x SIZE slot, but not the lanes to accommodate 16x speed. Page 2-20 and 2-21 of your manual go into the details you need for your motherboard.

Note that if 4 lanes are used for the secondary adaptor, then there are only 2 lanes left which can be used in the slots above the primary graphics slot. If you do not use the secondary graphics adaptor you can use a PCIe peripheral in the secondary slot up to 4 lanes and still have 2 lanes left for the upper slots. This is for your motherboard.

With all that said you have a 16x blue slot and a 4x black slot.

iMogal · 11-10-2007, 01:53 PM

Okay, on the ASUS Maximus MoBo, there is two x16 PCIe slots. (Looks like a nicer board too)
I 'should' be able to plug the card into the lower 16x slot and it'll still work properly (at full speed) ?

Nice O/C review over here on the Maximus: Clunk.org.uk

zapionics<alt> · 11-10-2007, 04:09 PM

Guys, the board manufacturers are doing all sorts of things; taking all sorts of shortcuts to suit the board design, costs, etc, Shaihulud has listed some of the dependancies.

Just bench both slots (assuming they are both x16 which you can tell from the manual, box, marketing, etc) with 3dmark so you KNOW which is best rather than guessing.

*SRTDodge05* · 11-10-2007, 08:10 PM

Quote:

Originally Posted by iMogal

Okay, on the ASUS Maximus MoBo, there is two x16 PCIe slots. (Looks like a nicer board too)
I 'should' be able to plug the card into the lower 16x slot and it'll still work properly (at full speed) ?

Nice O/C review over here on the Maximus: Clunk.org.uk

If you plug it in the second slot i think its only going to run at 4x.

traveler · 11-10-2007, 10:24 PM

The Asus Maximus Formula, Asus's new X38 chipset mobo, does have two full speed 16x slots.

The P5E has three 16x slots, but two run at the full 16x and one runs at 4x.

shaihulud · 11-11-2007, 08:37 AM

Since Intel still uses the North and South core logic architecture you need to remember the South lanes too. The X38 (North bridge) does have 32 PCIe v2.0 lanes for PEG only, and the ICH9 (South bridge) has 6 PCIe v1.1 lanes routable. This is why the P5E can support up to 3 graphics cards due to the extra x16 size slot installed on the motherboard. 4 lanes have been routed to that slot because of the ICH9 and can be used for up to a 4 lane peripheral. However, one caveat, only 2 slots, which are PEG only, can be up to revision 2.0, but a revision 2.0 will work in a revision 1.1 slot at later specs. Note, that it will have to cross the DMI to access memory.

iMogal · 11-11-2007, 02:59 PM

So, altimately, the video card will work in any PCIe port.
The speed of the port is the detering factor.

So with the Asus Maximus MoBo, with two 16x PCIe ports,
it wont matter what 16x port I put it in,
it will work at the full 16x speed with no problems.

Thats what I needed to know!

(although I now may wait on the x48 chipset)

but this info will pertain to any build I make.

11-09-2007, 11:15 AM	#1
iMogal Zoom Zoom... Join Date: Oct 2002 Location: Canada Posts: 1,182	Which PCIe 16x Slot? Hey guys Does it matter what 16x PCIe slot you plug a single graphics card into? Say on the P5K Prem, can a single Gfx card be plugged into the lower slot? or does it have to be the upper one? My reasonning is because of my case. (Silverstone LC16M) If I can slide the vid card into the lower 16x PCIe slot, I can get an 8800 series into my case. In the upper slot, it wont fit, its too long. Other wise, I'm kinda stuck with a physically smaller (8600 series) card. __________________ SilverStone LG-08 Asus P5E-VM HDMI Intel e2180 O/C'd 2.85Ghz (8x355) 2x2Gb G.Skill DDR2-1000 (5,5,4,14) (2:3 533Mhz) Maxotr 120 Gig SATA 8Mb HIS 3870 Iceq3 Turbo 850 Corsair HX620 Modular PSU Dell UltraSharp 2407FPW Monsoon MM-700 2.1 Speakers __________________ PC = Box of lost hours
(Offline)

11-10-2007, 12:53 AM	#2
iMogal Zoom Zoom... Join Date: Oct 2002 Location: Canada Posts: 1,182	Re: Which PCIe 16x Slot? No one? Can someone try for me and see? __________________ SilverStone LG-08 Asus P5E-VM HDMI Intel e2180 O/C'd 2.85Ghz (8x355) 2x2Gb G.Skill DDR2-1000 (5,5,4,14) (2:3 533Mhz) Maxotr 120 Gig SATA 8Mb HIS 3870 Iceq3 Turbo 850 Corsair HX620 Modular PSU Dell UltraSharp 2407FPW Monsoon MM-700 2.1 Speakers __________________ PC = Box of lost hours
(Offline)

11-10-2007, 01:55 AM	#3
zapionics<alt> <unknown level> Join Date: Dec 2002 Location: AUSTRALIA Posts: 2,937	Re: Which PCIe 16x Slot? It shouldnt make any difference which slot you use so long as they are both 16x. Having said that, sometimes the motherboard manufacturers do silly things, so it may be worthwhile to try both and do a bench (3dmark) and see if there is any difference. __________________ "To Boldly Go..."
(Offline)

11-10-2007, 03:10 AM	#4
traveler Where to next? Join Date: May 2001 Location: South Florida Posts: 18,167	Check the manual and make sure that both slots are true 16 slots and don't just look like 16 slots.
(Offline)

11-10-2007, 07:26 AM	#5
shaihulud Registered User Join Date: Jan 2005 Posts: 1,239	Re: Which PCIe 16x Slot? Always check the manual to confirm the routing and electrical specifications of the slot. PCIe is often quoted as it will work and route to but this is not always true. This is especially important if integral PCIe peripherals are using the lanes that would be allocated to the slot. You may note in the manual that particular slots only can support so many lanes or electrical. Just another caveat, some lanes have a different mapping to memory, and some have to go thru other buses.
(Offline)

11-10-2007, 09:54 AM	#6
iMogal Zoom Zoom... Join Date: Oct 2002 Location: Canada Posts: 1,182	Re: Which PCIe 16x Slot? The manual doesn't say anything about single card use. The board does have 2 PCIe x16 ports. When setting up a xfire thou, the say to use the primary PCIe port for the master gfx card... So other then that... ? uhm.... __________________ SilverStone LG-08 Asus P5E-VM HDMI Intel e2180 O/C'd 2.85Ghz (8x355) 2x2Gb G.Skill DDR2-1000 (5,5,4,14) (2:3 533Mhz) Maxotr 120 Gig SATA 8Mb HIS 3870 Iceq3 Turbo 850 Corsair HX620 Modular PSU Dell UltraSharp 2407FPW Monsoon MM-700 2.1 Speakers __________________ PC = Box of lost hours
(Offline)

11-10-2007, 10:03 AM	#7
SRTDodge05 Grab Life By The Balls Join Date: Jan 2003 Location: Michigan Posts: 7,830	Re: Which PCIe 16x Slot? 2 x PCI Express x16 (blue x16 mode, black x4 or x1 mode)
(Offline)

11-10-2007, 12:42 PM	#8
shaihulud Registered User Join Date: Jan 2005 Posts: 1,239	Re: Which PCIe 16x Slot? The P35 has 16 PCIe lanes for PEG only. The ICH9 has 6 PCIe lanes that are routable. Your mother board has an extra 16x SIZE slot, but not the lanes to accommodate 16x speed. Page 2-20 and 2-21 of your manual go into the details you need for your motherboard. Note that if 4 lanes are used for the secondary adaptor, then there are only 2 lanes left which can be used in the slots above the primary graphics slot. If you do not use the secondary graphics adaptor you can use a PCIe peripheral in the secondary slot up to 4 lanes and still have 2 lanes left for the upper slots. This is for your motherboard.
(Offline)

11-10-2007, 01:53 PM	#10
iMogal Zoom Zoom... Join Date: Oct 2002 Location: Canada Posts: 1,182	Re: Which PCIe 16x Slot? Okay, on the ASUS Maximus MoBo, there is two x16 PCIe slots. (Looks like a nicer board too) I 'should' be able to plug the card into the lower 16x slot and it'll still work properly (at full speed) ? Nice O/C review over here on the Maximus: Clunk.org.uk __________________ SilverStone LG-08 Asus P5E-VM HDMI Intel e2180 O/C'd 2.85Ghz (8x355) 2x2Gb G.Skill DDR2-1000 (5,5,4,14) (2:3 533Mhz) Maxotr 120 Gig SATA 8Mb HIS 3870 Iceq3 Turbo 850 Corsair HX620 Modular PSU Dell UltraSharp 2407FPW Monsoon MM-700 2.1 Speakers __________________ PC = Box of lost hours
(Offline)

11-10-2007, 04:09 PM	#11
zapionics<alt> <unknown level> Join Date: Dec 2002 Location: AUSTRALIA Posts: 2,937	Re: Which PCIe 16x Slot? Guys, the board manufacturers are doing all sorts of things; taking all sorts of shortcuts to suit the board design, costs, etc, Shaihulud has listed some of the dependancies. Just bench both slots (assuming they are both x16 which you can tell from the manual, box, marketing, etc) with 3dmark so you KNOW which is best rather than guessing. __________________ "To Boldly Go..."
(Offline)

11-10-2007, 10:24 PM	#13
traveler Where to next? Join Date: May 2001 Location: South Florida Posts: 18,167	Re: Which PCIe 16x Slot? The Asus Maximus Formula, Asus's new X38 chipset mobo, does have two full speed 16x slots. The P5E has three 16x slots, but two run at the full 16x and one runs at 4x.
(Offline)

11-11-2007, 08:37 AM	#14
shaihulud Registered User Join Date: Jan 2005 Posts: 1,239	Re: Which PCIe 16x Slot? Since Intel still uses the North and South core logic architecture you need to remember the South lanes too. The X38 (North bridge) does have 32 PCIe v2.0 lanes for PEG only, and the ICH9 (South bridge) has 6 PCIe v1.1 lanes routable. This is why the P5E can support up to 3 graphics cards due to the extra x16 size slot installed on the motherboard. 4 lanes have been routed to that slot because of the ICH9 and can be used for up to a 4 lane peripheral. However, one caveat, only 2 slots, which are PEG only, can be up to revision 2.0, but a revision 2.0 will work in a revision 1.1 slot at later specs. Note, that it will have to cross the DMI to access memory.
(Offline)

11-11-2007, 02:59 PM	#15
iMogal Zoom Zoom... Join Date: Oct 2002 Location: Canada Posts: 1,182	Re: Which PCIe 16x Slot? So, altimately, the video card will work in any PCIe port. The speed of the port is the detering factor. So with the Asus Maximus MoBo, with two 16x PCIe ports, it wont matter what 16x port I put it in, it will work at the full 16x speed with no problems. Thats what I needed to know! (although I now may wait on the x48 chipset) but this info will pertain to any build I make. __________________ SilverStone LG-08 Asus P5E-VM HDMI Intel e2180 O/C'd 2.85Ghz (8x355) 2x2Gb G.Skill DDR2-1000 (5,5,4,14) (2:3 533Mhz) Maxotr 120 Gig SATA 8Mb HIS 3870 Iceq3 Turbo 850 Corsair HX620 Modular PSU Dell UltraSharp 2407FPW Monsoon MM-700 2.1 Speakers __________________ PC = Box of lost hours
(Offline)

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