What are PCI Express 4x slots made for?

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?

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

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

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.

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

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.

is that the slot the soundmax normaly sits in ?

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.