PCI Questions

[Brian Blankenship]

Got a question about PCI Express x16 slots.

Can PCI Express x4 cards work in an x16 slot?

 

If they can then this solves so many issues for me.

[minibois]

Yes?
What would make you think 16X PCIE slots are not made for 16X PCIE cards?

 

Keep in mind that if you start adding multiple cards, some slots might become 8X slots.

[Brian Blankenship]

6 minutes ago, Minibois said:

Yes?
What would make you think 16X PCIE slots are not made for 16X PCIE cards?

 

Keep in mind that if you start adding multiple cards, some slots might become 8X slots.

Sorry, typo.

 

Can PCI Express x4 cards work in an x16 slot?

[MadModder]

No. The pins are used differently even if the card fits. PCI is a parallel interface (uses all pins for each signal), PCIE is a serial interface (uses multiple independent lanes).

 

edit: you added the above post while I was typing. Now I'm confused as to the specifics of your question. If you're talking about a PCIE component inserted into a PCIE socket, the answer is yes. You could put a PCIE x1 card in a PCIE x16 slot, and it will work.

[minibois]

2 minutes ago, Brian Blankenship said:

Sorry, typo.

 

Can PCI Express x4 cards work in an x16 slot?

Aha, there is the catch!

 

But the answer still remains yes  

PCIE is not really that picky about it the port or card, it can work both ways. The first (usually the smallest part) of PCIE is power, the rest is all data. The smaller the card or smaller the port, the less data bandwidth (of course limited by the smaller of the two).

 

Just so we're talking about the same thing, you do mean a PCIE 4X in a PCIE 16X slot and not PCI (not the express version).

[Bananasplit_00]

yep, no problem what so ever

[Brian Blankenship]

What I need to do ( hope will work )

 

Is put this card (or one like it)

http://www.ebay.com/itm/Chelsio-T420-BT-Dual-Port-10GbE-Unified-Wire-Adapter-Card-10-gigabit-NIC/142484782493?epid=1079297865&hash=item212cc13d9d%3Ag%3ANhgAAOSw-81ZndUb

 

in one of the PCIE slots on a mainbouard like this (Black/Gray, I know the big white one won't work):

https://www.newegg.com/Product/Product.aspx?Item=N82E16813135355

 

I just can't find anything saying they are in fact compatible, but I'm also not sure I know what I'm looking for. I missed almost all of PCIE, the last hish speed slots I dealt with untill recent were AGP... Don't ask.

[mariushm]

PCI Express is designed from the start as "modular" , meaning the "physical" shape of the slot is separate from the "electrical" format of the slot.

 

A pci-e x16 (physically) slot can be electrically x1, x4, x8 or x16 inside the slot

A pci-e x8 (physically) slot can be electrically x1, x4 or x8

A pci-e x4 (physically) slot can be electrically x1 or x4

 

Because of this any card that you plug into the slot must be able to communicate with the CPU at least using x1 and then auto detect how many links (lanes is the term) are available in the slot and use all of them (or as many as it's capable - for example the gpu chip in RX 460 or RX550/560 can only use up to x8 lanes even when plugged into a x16 slot)

.

So you can plug a card that's capable of max x1 or max x4 in a pci-e x16 slot and it should work.

For the same reason, as long as the physical slot has no end wall and there's no components on the motherboard blocking things, it's perfectly safe to insert a pci-e x4 card into a x1 slot,or x16 card into a x4 slot,and they'll work.

 

See from around 1:30

 

 

 

 

Well, they'll start, pc will start, card will initialize but the card's driver may refuse to work saying there's not enough bandwidth for example (but the point is nothing bad will happen)

 

Now, there are some exceptions.

On most motherboards a few pci-e lanes are offered directly by the cpu and are a bit special as in they're meant for graphics cards. So for example, in the pci-e x16 slot closest to the cpu, you may only be able to make work graphics cards.

Some motherboards will have two pci-e x16 for SLI, Crossfire... they're physically x16 slots but the number of lanes (16) is shared by the slots, so if you insert two graphic cards each slot is auto converted into x8 electrically.

Again, on some motherboards you may only be able to insert graphics cards in those two pci-e x16 slots, otherwise computer won't boot or the card won't be recognized.

 

anyway.. tldr yes, generally you can plug a x4 card into a x16 slot, no worries.