Other Uses for an AGP Slot?

SleepyHappyDoc asks: "AGP seems to be going the way of the dinosaur, but there's still a lot of slots on legacy motherboards out there. If you don't have need for the graphical advantages of AGP (say, on a headless server), what else could you use the AGP slot for? Could the advantages of AGP over PCI be leveraged in a use other than graphics cards?"

Running a vintage AGP card?

[FatSean]

I would think that perhaps you could use the bus bandwidth and an old/slow card to do additional computation. Leverage the GPUs in the more recent AGP 3D offerings and use it for something...uh....usefull :)

Perhaps we can user in a new age of game design where you can load your machine up with older cards to assist with the heavy 3D math for a game, or maybe expose those cards as a virtual machine of some sort.

No.

[Anonymous Coward]

AGP's architecture makes it unsuited for bi-directional communication. For what it would cost to fabricate an AGP card you could buy a PCI-Express mobo+card.

Co-CPU.

[SharpFang]

I don't know of any non-gfx cards that would use the CPU but there was a C compiler released that would use the GPU instead of CPU for your generic computations (instead of 3d gfx) and for certain kinds of calculations/programs it would be equivalent of 10GHZ P4 class CPU in the means of speed. Look up archives of Slashdot for it.

VRAM Storage Device

[dastrike]

Well, this still involves to use a graphics card, but in a bit different way.

1. Acquire a cheapo graphics card with lots of memory, e.g some low-end NVIDIA or ATI with 256 megs
2. Read and apply VRAM Storage Device - How to use the memory on GFX board in a different way... [linuxnews.pl]
3. You have a bunch of memory that can be used for a ramdisk type of device or swap space

YMMV with the performance though.

Not a lot

[Kijori]

AGP is a one-way architecture - the motherboard sends data to the graphics card, the graphics card processes it and sends it to the monitor. The limitations of this way of working are why dual graphics card solutions were never practical on AGP once you started increasing the complexity of the data - the bus wasn't capable enough.

That said, it's not impossible to get it working. You just need to get around the one-way bus problem. There are two obvious solutions for this, to my mind: (ignoring the fact that no cards exist to do it for you)

Use it for one way data
You create a card that acts only to process and send away data. At its simplest, this might be an audio card (without line-in, obviously). Getting slightly more creative, the card could take the 'load' of preparing documents and printing them off the CPU, although I can't see this being useful. Using a rather crossfire-like setup, you could send the output of a suitable graphics card into an input on another, and use it as a pre-processor; at its most basic this could be used to divide a signal in half to be processed by two (or more) cards, or getting more complex it could render something simple - perhaps hidden windows, for use in transparency effects, or perhaps acting as a 2D processor and leaving 3D work to the 'bigger' card - tag this as 'rendered' and send the output to its big brother.To be honest though, this seems a little ridiculous.

Creating a feedback path for 2-way data
This, in my opinion, is where it could be useful. The moment you add a way to send data back - at its simplest, I suppose this would be a SATA or IDE cable and suitable software that continuously reads the contents of the 'hard disk' - you have an opportunity for a specialised processor. The hack would be incredible difficult, granted, but the processor on a graphics card would seem to be well suited to encode video. You send your stream to the AGP card, it converts it to mpeg4 (for example) and sends it back via SATA, taking 99% of the load off the processor. (These cards have recently started to appear for PCIe, so the is definitely a market). With some sort of feedback path, the card could do anything a PCI card can do, but substantially faster thanks to AGP's higher bandwidth - the trick is getting a decent feedback loop.

After all that, though, I think the practical answer is no, there is no use for an AGP slot other than graphics; there is no demand for other cards, so they just don't exist.

Re:No.

[SharpFang]

bidi is not everything. If you have a 33k modem connection to a 256-node beowulf cluster, do you claim it's useless? AGP cards have pretty beefy serial processing chips, that can be programmed with any, generic tasks just like CPUs, and for some of these tasks they will suck a big time (but still work) and for some they will rule (stuff like lots of similar rather simple calculations on lots and lots of data - they are unbeatable.) Statistics, rendering, filtering, encoding/decoding, all such stuff is really fast. Now the downstream is pretty slow so it hurts that -very- simple calculations can't be done en masse (the GPU can do them great but they get stuck at sending them back to the PC), and hard calculations with lots of decision-making are better handled in the CPU but there is a class of tasks where the GPU is unbeatable.

Video compressor

[Anonymous Coward]

Many seem to be saying that the AGP has a lot of bandwidth going TO the card but not coming back from the card. This seems well suited to feed uncompressed video to a card in the AGP slot, have the AGP card compress the video into whatever format you wish, and then send back the compressed data.

Sigh you make a lousy hacker

[SmallFurryCreature]

I got an old dual p3 wich is limited to 768mb. Anymore and it won't even boot.

So how would propose I add another gig when it cannot even accept a single gig?

It does however have a 32mb graphics card that is not used. Oh sure it is a tiny amount of memory but when the kernel is forced to start swapping it makes a difference. Not a huge amount to be sure and it doesn't help at all when it really needs to swap a lot but it gives me just a little bit more room to play with.

Haven't thought about upgrading the card but I guess if I ever see a really cheap 256mb card it might be worth it.

A dual P3 is still plenty fast for desktop use especially since the linux kernel keeps on improving. Windows users may wish to close their ears to save themselve from terminal shock but linux installs get better with age.

Sure sure someday I am going to have to buy a new system and now that dual core chips are here the hurdle is not as big as having to buy a dual single core machine was but still, the longer I can keep this system running the happier I am

Hardware/software hacking is about making stuff go that extra mile. Just plonking a wad of cash on the counter is totally missing the point.

Re:Not a lot

[DRJlaw]

AGP is a one-way architecture - the motherboard sends data to the graphics card, the graphics card processes it and sends it to the monitor. The limitations of this way of working are why dual graphics card solutions were never practical on AGP once you started increasing the complexity of the data - the bus wasn't capable enough.

No.

AGP is a two-way, point to point architecture that has a single master and a single target. Data can be written to and read from the graphics card memory, but you can't exercise the full range of PCI I/O operations. The data transfer rates are asymmetric, with sending data to the card greatly favored over reading data from the card, but they are most certainly two-way.

The SLI argument is a lesser error, if you would even call it that. You could have, but never as far as I know actually did have two AGP busses in a system. Thus I suspect that it would have been possible to do SLI with AGP, especially when you consider that existing implementations of SLI require an additional card-to-card link, which means (likely, this last part is speculation) that there is very little return data being transmitted from the cards back to the PCI express switch beyond that which you would see in a single card system, whether it is PCI express based or AGP based.

Headless, then...

[chivo243]

Gotta have'm, 90% of our servers are now running headless(yikes) where have all the monitors gone? As for all the other slots, I guess it was poor planning from the beginning. But if you look at the market as being constantly in the state of BETA! then it all makes fucking sense.... just my two euro cents. Wait a damn, minute, as long as I have been drinking, and can type..Does the fact that MS has stopped support for some OS's now and others soon, that they have finally found all the bugs, and do not need to support their product???

Re:Ask Slashdot ...

[Forbman]

VESA Local Bus did have various other cards besides video cards available for it, including high performance disk drive controllers. AGP's design was deliberate by Intel to really only be useful for video cards, such as its mostly one-way data flow. Intel wasn't too happy with the VLB design, which was pretty much a hack, and also that it couldn't control how it was used, and was concerned about the power requirements and having to design for potential bad VLB card designs to protect itself.

Other uses for AGP slot. Some are practical.

[GrpA]

First, install a used graphics card. Then reprogram the graphics card to do other stuff.

Any time domain project might work.

eg,
Audio Card. (Yes, you can produce audio on a graphics card).
Signal Generator (All kinds of repetative signals you can generate)
TV Remote (Just connect to a IR led on the output port).
Digital TV Modulator. http://www.hackaday.com/entry/1234000113073480/ [hackaday.com] This is the Best idea made practical.
Transmitter (on MANY different frequencies).
Ultrasonic transducer driver for driving 3 ultrasonic transducers. (Spot sound)

Just keep in mind you have 3 Digital to Analogue Controllers,
Programmable clocks
Memory (and a means of moving it to the DACs)
and two other digital outputs,

ALL PACKED NEATLY INTO A VIDEO CARD FORMAT... and it even works with AGP. :)

GrpA