PCI-E x4 into PCI-E/PCI-E 2.0 x16 socket

[xavxen]

Hi guys,

Im looking to install an Adaptec 1430SA RAID card into a new setup. However, the interface is PCI-E x4. Im looking to put it into an Asus P5Q E motherboard which has 2 x PCI-E 2.0 (x16) and 1 x PCI-E x16. I was just wondering if it is safe/viable to put the x4 card into one of these slots?

Many thanks!

[kalniel]

Yes, safe and viable.

[pollaxe]

^ Yep, what Kalniel said..
Generally speaking you can put lower speed rated PCIe cards into higher rated slots. We've done it at work a number of times, the only flies in the ointment have been the odd Dell server which didn't want to co-operate but that's a typical Dell thing anyway..

[xavxen]

Excellent, thanks for the swift replies!

[oolon]

Unlike graphics cards which just wire up everything available giving x16 cards even for things that can never use the bandwidth, RAID cards wireup what they require in your case a x4 card, the thing to watch out for is putting a gen2 card into a gen1 slot, as this will half the amount of bandwidth available to a level where it is less than the card really needs. You will find some raid cards which say, x8 in a gen1 slot and x4 in a gen2.

[shaithis]

Also, even though the slots on your motherboard are 16x "length", I would expect that one or more of them are not 16x electrically connected (sometimes they are 8x or 4x).

Make sure you know exectly what the slots are so that you can decide the best way to fit your cards in, especially if you think you may add another PCI-Express card at a later date.

[Syllopsium]

Hi guys,

Im looking to install an Adaptec 1430SA RAID card into a new setup. However, the interface is PCI-E x4. Im looking to put it into an Asus P5Q E motherboard which has 2 x PCI-E 2.0 (x16) and 1 x PCI-E x16. I was just wondering if it is safe/viable to put the x4 card into one of these slots?

Many thanks!

Yes. It actually works both ways in a number of cases. Sticking an x16 (length) card in a <x16 (length) socket won't work (it won't fit), but sticking either <x16 (length) into x16 length will.

Likewise, not only will an electrically x1 (soundcards, some network cards) work in a > x1 PCI-e slot, but quite often cards that support x16 will negotiate down if stuck in say a x4 slot. This includes many graphics cards - obviously performance is impacted, but if you're not looking to run high end games it could be a good solution for multiple monitor support, etc.

If you think about it, plenty of people already run in this configuration. Until recently multiple x16 electrical slots weren't supported when one of the slots was already in use. The D975XBX2 I have features three x16 long slots. One is always electrically x4, the other two are either x16 and x1, or if you are running Crossfire, typically x8 and x8.

PK