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What are PCI Express 4x slots made for?

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June 9, 2009 5:47:01 AM

I have a PCI Express 4x slot on my Asus Crosshair motherboard. It is open ended, but there are capacitors directly behind it blocking any 16x cards. So, what are PCI Express 4x slots for? What would I put there?

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a b V Motherboard
June 9, 2009 6:56:16 AM

Hi D

The PCI Express 4X connector has 64 pins and is intended to be used on servers, but not limited to servers:

- PCIe x1 card in a PCIe x16 slot will run at PCIe x1 speeds
- PCIe x16 card in a PCIe x16 slot will run at PCIe x16 speed.
- PCIe cards are all backwards compatible, as in a x1,x2,x4,x8 cards will all work in a PCIe x16 slot
- x1,x2,x4 will all work in a PCIe x8/x16 slot
- x1,x2 will all work in a PCIe x4/x8/x16 slot
- x1 will all work in a PCIe x2/x4/x8/x16 slot
June 9, 2009 7:24:53 AM

As starams5 mentioned, you can use 1x, 2x and of course 4x in a PCIe 4x slot.
Cards that are made using those can include (but not limited to) SAS/SATA RAID controller, sound card, dedicated A/V encoders, TV tuner..etc.

It just so happens PCIe 16x is mostly used by graphic cards and that's what most users see.
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a b V Motherboard
a b Ĉ ASUS
June 9, 2009 7:33:31 AM

future hardware, or atm raid cards etc

im supprised nvidia and ati arnt making basic dual display cards for pcie 1x/2x/4x especially for workstations etc needing more monitors
a b V Motherboard
June 9, 2009 4:39:22 PM

if you are lucky like me, my server's pci-e 4x slot is open ended, meaning i can put any card in (though at reduced speed if it requires 8x or higher)
June 9, 2009 4:58:13 PM

Thanks for the replies.

Unfortunately the slot is blocked off by capacitors, so no 8x/16x cards will fit. It seems like every mobo I see has raid built in, so why would need an extra raid card? I guess I'll just treat it like an excess 1x slot. But I never even use my 1x slots.
a b V Motherboard
June 9, 2009 5:15:54 PM

The 1x slot is cool, I decided to take advantage of it. My Xonar D2X works well in the 1x slot, sits above all others allowing more space and air flow below.
June 9, 2009 5:43:33 PM

My 1x slot in the HTPC is used by a DVB-T tuner card for example

Quote:
It seems like every mobo I see has raid built in, so why would need an extra raid card?

The software RAID solution which consumer chipset uses functions serves a totally different purpose compared to expensive hardware RAID needed by servers for reliability reason. Also useful for migrating RAID arrays between different motherboards that have different chipset.
a b V Motherboard
June 9, 2009 7:24:08 PM

Dougx1317 said:
So, what are PCI Express 4x slots for? What would I put there?


Hardware RAID controller
Gigabit NIC
TV Tuner
10GBe Fiber channel controller

November 21, 2009 9:51:25 PM

starams5 said:
The 1x slot is cool, I decided to take advantage of it. My Xonar D2X works well in the 1x slot, sits above all others allowing more space and air flow below.





is that the slot the soundmax normaly sits in ?
a b V Motherboard
November 22, 2009 1:41:41 AM

kevchat said:
is that the slot the soundmax normaly sits in ?


That little sound card uses the x1 slot as well. If you have an older board that came with the SoundMax audio card, the x1 slot was useless because the x1 slot was positioned on the board exclusively for the SoundMax card. ASUS has since made changes to the design to allow other x1 cards to work in the slot. I tried to link you to a pic of the P5N32-E SLI Plus which has offset x1 slots, but maybe I did it wrong.

November 22, 2009 3:47:35 AM

My Asus Crosshair is that way. I can't use the slot for anything else, and I can't put the soundmax card in any other slot.
a b V Motherboard
November 22, 2009 4:48:28 AM

Dougx1317 said:
My Asus Crosshair is that way. I can't use the slot for anything else, and I can't put the soundmax card in any other slot.


Funny how things changed when they came out with the Xonar, there would have been some pissed off D2X customers.
November 8, 2012 11:41:29 PM

PCIe x4 is mostly for server grade network cards.
December 3, 2012 11:40:08 AM

The ROG Crosshair V has the PCI-E 4speed lot for a special network and audio card (That is currently NOT on the market and only comes with certain ROG Special edition motherboards.
The card is called the "RoG Thunderbolt"
That is why it has that fancy slot :D  (That slot was specifically designed for the card(not the slot specifically but there are certain I/O slots on the motherboard right next to it that attach to the ROG THunderbolt))
!