If you just modify the slot on the motherboard then you can use the card at x16 speed later in a different system.

Snipping off part of the card's edge connector has the risk of inadvertently destroying the other "pins" and/or PCB traces. It also means the card will no longer ever be an "x16 card" if one day you decide to reuse it elsewhere. It might be useful if there are tall capacitors/other components in front of the slot on the board that get in the way of the "full size" x16 connector on the card.

Meanwhile, putting a dremel to the edge of the MB's x8 slot means you're just cutting plastic; it ought to be easier, and doesn't run the risk of permanently degrading anything (so long as you're careful). Plus, as you said, there certainly do exist such "open-ended" x1/x4/x8 slots on various boards; it almost seems guaranteed to work the first time.

With these in mind, modifying the slot appears to make more sense.

But, there is no point in doing this.
Almost all "PCI-E 8x" type slots are designed to be x8 electrical and x16 mechanical (so there is no need to modify them) OR are full x16 electrical however half of PCI-e lanes are shared with something else (and if connected it makes x16 into x8 one).

The only place where mechanical "8x" are a thing, is server and some OEM board, and moding PCI-e slot can be difficult (since you have to cut back of slot without damaging pins inside).

Also, most vendors on modern boards use open ended PCI-e slots.

SW-SSG wrote:

With these in mind, modifying the slot appears to make more sense.

Hm, yeah this does seem to be the least destructive/most reusable way to go. I'm just worried about Shaky Hands McGee here potentially slipping and dremelling off a pin near the end of the connector or possibly another component on the motherboard. But as you mentioned, the same could be said for slipping while trimming the card edge connector on the card too.

So, I guess I just have to be careful.

agent_x007 wrote:

But, there is no point in doing this.
Almost all "PCI-E 8x" type slots are designed to be x8 electrical and x16 mechanical

Nope, 8x mechanical connector.

agent_x007 wrote:

The only place where mechanical "8x" are a thing, is server and some OEM board,

Bingo.

Why not get a riser card and cut it up.

Edit
Wasn't there a lanparty baord that had an pci-e 8x slot?

Jade Falcon wrote:

Why not get a riser card

Yeah, I could even do something like this http://www.dx.com/p/pci-express-pci-e-8x-to-1 … 42#.WfjVy3MaXqA
And make no potentially hazardous cuts at all... the card in question even has a low profile bracket so it would even fit all neat... but see that involves time and money 🤣 (I got the motherboard for free and if you count that I already had the card lying around as free then even $5 is infinitely more than I spent on the board amd card)

They have those adapter cable for 1x to 16x slots as well. Mounting cards using it might be a pain.

Mounting cards is a bit of a pain, but does work, see :

That's two GTX480 on two separate ribbon adapters - one 16x to 16x (to move the card over to the right), and one 4x to 16x. I used long screws to hold them in, plus the PCI-e power connectors can also be used to ensure they stay in the correct position. I operated like that for at least a couple of years, although I'm glad on my new system I don't need to do that.

At the time I didn't have a dremel, and using a knife seemed right out. If you were careful and used the dremel on slow I suppose it could work well.

why not a riser card like I said?

Use an exacto knife and just cut a groove on the PCIe slot.

The real problem will be GPU sag.

Jade Falcon wrote:

why not a riser card like I said? https://ae01.alicdn.com/kf/HTB1jWCSdywIL1JjSZFsq6AXFFXaX/PCI-e-PCI-Express-font-b-8X-b-font-to […]
Show full quote

why not a riser card like I said?

Hm I actually didnt know something like that existed.. I thought you were just talking about the ribbon cables. I asume that effectively converts the port to a low profile port...

Basically, yes, although they can be less physically stable than a ribbon cable option - best for desktop cases rather than systems with cards hanging horizontally.

Its not that tall, but yest you do run into problem with everything lining up with the case on some setups.
But most of the time if the VGA/DVI ports are not to close the the edge all you need is a longer screw to hold the card down.

I'm telling y'all, easiest way is to exacto knife the PCI-e slot on the motherboard and cut a groove. No need to hassle with risers, converters, and other stuff. Everything screws in fine.

We do this at work with production Supermicro/Dell servers all the time (before 16x mechanical friendly slots were mainstream).

dexvx wrote:

I'm telling y'all, easiest way is to exacto knife the PCI-e slot on the motherboard and cut a groove. No need to hassle with risers, converters, and other stuff. Everything screws in fine.

We do this at work with production Supermicro/Dell servers all the time (before 16x mechanical friendly slots were mainstream).

Wile this does work, not everyone wants to take a knife to their motherboards, that and the extra length of the pci-e slot on the card can get in the way of parts on some boards.
If you ok whit taking a knife to a motherboard this is certainly the best way of doing it for most setups.

Jade Falcon wrote:

If you ok whit taking a knife to a motherboard this is certainly the best way of doing it for most setups.

Yes sir I am OK with taking a knife to the board... more so than a Drexel tool which was the original plan. I like the knife plan better. I don't think there are any components (caps, etc.) in the way of having a 16x sized card inserted in the 8x slot.

If you can, take a look at modern motherboard's PCIe 1x slots. The way they are made now is that there is a groove cut at the end of the physical slot. Key is to not touch any of the metal pins. For dremel, it's probably the fastest (and neatest) if you have something that can do it that small.

I would use a dremel with a tip like that triangular one to cut the groove, very easy to do without too much fear of ruining anything.