In some computercases you’ll find a bracket in which the fin can slide into. It will provide extra physical stability and avoid sagging of the card. Usually you don’t see this on consumer hardware, it’s more common in workstations.

Having said that the latest cards like the GeForce 4080/4090 come with an anti-sag bracket as well since those cards are very long and heavy.

It's exactly what Thandor said, there should be no speculation about it. It's meant to make the card "full length", because some cases have a place in their front area to physically support such cards.

Are these cases following some standard, or each vendor has its own standard?

Do you have a photo of the fin being used as its intended? I've never seen one in their respective case.

The length of a "full length" card is standard, more or less. So case manufacturers make their own solutions for supporting them.
Here's a random photo from the internet showing a case that has support for these cards. The fin slides in and the card gets additional support so that it doesn't sag and bend.

konc wrote on 2024-09-02, 11:01:

The length of a "full length" card is standard, more or less. So case manufacturers make their own solutions for supporting them.
Here's a random photo from the internet showing a case that has support for these cards. The fin slides in and the card gets additional support so that it doesn't sag and bend.

This is a really hefty system for a random internet photo-- Dual Voodoo2 with the longest SLI cable I've ever seen, gold memory heatspreaders, and that CPU HSF is gorgeous!

ooooooh lmao that is crazy I've never noticed that 😁 thanks!

Wes1262 wrote on 2024-09-02, 10:25:

I've asked a bunch of knowledgeable people and I got so many contradicting answers!
Some don't make much sense to me like improve air flow... or it's an additional heatsink... but it's not really touching the card in many cases!
What is the real reason fins exist?

That looks like an Apple ATI card for a late 2000s Mac Pro 4,1 or 5,1, no?

I'm pretty sure the Mac Pro has, like others said, a bracket where this is used to secure the card.

Also, you want an earlier example of this - go and look at the now-super-expensive (US$1000 buy-it-now-on eBay) Apple GF4 Ti4600 for the G4s. Has a super-long PCB, way longer than any PC version of the GF4 Ti4600, for the same reason.

Basically, the problem being solved is that in the late 1990s, one big reason for DOA computers was that video (or other cards) would get loose in shipping. So many large manufacturers have come up with various schemes to secure the cards better...

Wes1262 wrote on 2024-09-02, 10:56:

Are these cases following some standard, or each vendor has its own standard?

The standard has been set by the original IBM PC (model 5150), and every case that still has the card support slots uses the same distance from the back as IBM did. Back in the 80s, there were a lot of full-length cards, for example bot the MDA and the CGA card. Hard Cards with a hard drive mounted to an ISA card are another classic use of full length cards that require the support slot for mechanical stability. Thinking of a spinning hard drive mounted to the end of an 8 bit ISA card without physical support on that end makes me shudder...

Full length PCI card.
When put into a case that has full length PCI slot capability it supports the weight of the card and directs the airflow of the fan over the card.

Matrox Productiva G100 MMS has a handle on the end:

https://www.512bit.net/matrox/matrox_g100mms.html

Errius wrote on 2024-09-03, 21:31:

Matrox Productiva G100 MMS has a handle on the end:

https://www.512bit.net/matrox/matrox_g100mms.html

Its exactly the same.
The end of the handle thins at the end to act as a runner that fits into the slot in the case.

ElectroSoldier wrote on 2024-09-03, 21:43:

Errius wrote on 2024-09-03, 21:31:

Matrox Productiva G100 MMS has a handle on the end:

https://www.512bit.net/matrox/matrox_g100mms.html

Its exactly the same.
The end of the handle thins at the end to act as a runner that fits into the slot in the case.

Oh my god this makes so much sense now. Lmao. I would love to see a modern-ish card being slotted-in in a case though. Do any of you folks have a video showcasing this?

Wes1262 wrote on 2024-09-03, 22:25:

ElectroSoldier wrote on 2024-09-03, 21:43:

Errius wrote on 2024-09-03, 21:31:

Matrox Productiva G100 MMS has a handle on the end:

https://www.512bit.net/matrox/matrox_g100mms.html

Its exactly the same.
The end of the handle thins at the end to act as a runner that fits into the slot in the case.

Oh my god this makes so much sense now. Lmao. I would love to see a modern-ish card being slotted-in in a case though. Do any of you folks have a video showcasing this?

I have several cards that do this but no videos of it.

I dont know if these image links will work.

In the middle of the case on the left you can see the rails on the back of the fan shroud

On this card you can see the metal "handle", the end of it is thin enough to slide down into the rails in the case.

This is the same card (but with BBU fitted) in the same computer.

In the PC/XT days the cards you most needed to secure were usually the RAM cards and "HardCARD" HDD cards..... which you might need to bear in mind if you only get a couple of "holders" in a case.

And before that the IMSAI 8080 cards were all so long they also needed supporting. even though the cards stand up the back of the card still runs down a rail to support it.
Then PC/XT followed the idea and used it, and now the larger modern cards do it.

Not many of the large graphics cards of today use them because they tend to follow form first and function second even though the weight of the cooler clearly needs supporting.

Do modern cases still have these supports?

I have not seen these in anything that isn't some OEM case.