My motherboard have 3 pcie x16 slots, 1 for GPU, but what are the remaining 2 for?

[Dukesilver27-]

Motherboard: Asus Prime B660M-A D4 Wifi.

So, I'm rather new to mid-end builds, my previous motherboard was the H series ones, which lack features. Now with a mid-end motherboard, I'm rather confused about what the other 2 pcie x16 slots are for? Obviously crossfiire and SLI are not viable, so what for?

I'm wondering, whether this could be a future upgrade for me, I've been googling pcie x16 slot devices or parts, could not find a straight answer. 

[Electronics Wizardy]

One thing is those aren't x16 slots electrically. There x4 and x1 slots, just with a bigger physical connector.

 

But you can put any card you want in. GPUs, network cards, storage, sound cards, accelerators, and more.

 

Most all gaming pcs will just have it empty, motherboards have almost all you need built in now.

[RONOTHAN##]

9 minutes ago, Dukesilver27- said:

so what for?

Anything you can find. SSDs, capture cards, network cards, RAID cards, GPUs (assuming they don't need more than 4 PCIe lanes for good performance, those slots may be x16 in length but they're only wired for x4 and x1, it'll work no matter what it just might not be up to the performance you'd expect), whatever you can think of. That's the brilliance of PCIe, it can be adapted to basically everything.

 

For just a normal gaming system, none of those really matter, for 95% of gamers a motherboard could have a single x16 slot and an M.2 slot and be perfectly adequate, they're just there if in the future you think "man, I could really use an couple USB ports" or something along those lines.

[BobVonBob]

Basically they're there to give you access to more of the PCIe lanes your chip can provide or to allow people to mount the GPU in a different spot. Most people won't use them, but they can be used for things like extra NVMe drives, high speed networking, or more GPUs (for compute purposes, since SLI and crossfire are dead). Often they also aren't wired for the full x16 the physical connectors are capable of, but the plastic slots are relatively cheap and they physically secure GPUs better than the smaller versions of PCIe slots.

[Middcore]

To an extent the large number of PCIe slots on a standard ATX form factor motherboard is a holdover from the days when damn near "everything" was a card (although they didn't go in PCIe slots, we are talking before PCIe existed). Watch a retro build video on a channel like Lazy Game Reviews and gaze in awe at the stack of 5-6 cards in the machine. (Of course they all look pretty puny and unimpressive compared to a modern GPU, but it does make it easier to see why these things were called "cards" in the first place.)

 

But many of the functions you used to need a card for have now been absorbed into the motherboard itself. Audio is a good example. Sound cards used to be (talking the 90's into the 2000's here) essential, now the audio hardware built in to the board is good enough for the overwhelming majority and of the audiophile minority, most don't choose a sound card as a solution... there's only a couple of companies I can think of even still making sound cards and they're the same models they've been making for years. 

 

These days other PCIe devices to put in those slots like the ones @RONOTHAN## mentioned do exist and you might find some of them useful at some point (my wife's system has a PCIe wifi card in it, I've used cards to add additional internal USB headers in the recent past) but 90% of people will never put any PCIe devices in their builds except a single GPU.

 

This means that most people could get by with the lower number of PCIe slots offered by mATX and m-ITX form factors and never feel a lack. However, mATX has basically been pigeon-holed as a barebones budget option and m-ITX has other practicality and price drawbacks. 

 

 

[AnonymousGuy]

My desktop is using all the slots to the point I'm probably going to upgrade to Cascade Lake-X when that comes out next quarter:

 

GPU (obvious)

Sound Card (need SPDIF out)

P5800X SSD (obvious, it's limited by running at PCIe 3.0 though instead of 4.0)

10GB network (there's only a handful of mobos that have this built in, also being limited to x1 I think because Z690 doesn't have enough lanes)

 

My server is using most of the slots:

 

GPU

RAID card

10GB network

 

I'm actively annoyed at the number of motherboards that basically only have 2 slots nowadays but will have like 5 M.2 slots.  No one is  putting that many SSD's in their desktop.

[mike_seps]

I had to use one of mine to add a Type E (front USB C) header . Good old TUF gaming plus didn't come with a header, and I am not about to lose out on my USB C port

[RRareGamingOnYT]

On 7/27/2022 at 6:45 AM, Dukesilver27- said:

Motherboard: Asus Prime B660M-A D4 Wifi.

So, I'm rather new to mid-end builds, my previous motherboard was the H series ones, which lack features. Now with a mid-end motherboard, I'm rather confused about what the other 2 pcie x16 slots are for? Obviously crossfiire and SLI are not viable, so what for?

I'm wondering, whether this could be a future upgrade for me, I've been googling pcie x16 slot devices or parts, could not find a straight answer. 

You can use them for any other devices which use a pcie interface, also they arent 16x slots, they are pci x4 and x1 slots, you can connect network cards, sound cards, more ports, etc.