8x AGP for Dual Processing Systems?

Paul E. Loeb asks: "I am wondering if there are any solutions out there that will allow the use of an 8x AGP bus with dual processing support. I prefer AMD Athlon MP, but Xeon would be fine as well. I am looking to build a high-end graphics and video editing system, and I don't want to submit to a single Intel or AMD processor. I do however wish to use a Radeon 9700 or GeForce FX, but that would be pretty pointless at a 4x bus. Thank you in advance for all of your advice."

Comments

8X is a marketing feature

[Hythlodaeus]

I do however wish to use a Radeon 9700 or GeForce FX, but that would be pretty pointless at a 4x bus

Not according to most benchmarks I've seen. The AGP speed mainly comes into play when the VRAM can't hold all the textures, and the card has to go to main memory. When that happens, performance will suck no matter the AGP speed, but that should be very rare with the 128MB either of those cards would pack. 8x makes a negligible difference in benchmarks of current PC games. In other words, don't make AGP 8x a sticking point in a system that meets all your other needs.

Re:8X is a marketing feature

[spongman]

This is definitely the case for most applications where 128MB easily covers the texture requirements and the only speedup seen is for vertex/instruction buffers. However he specifically states that he's doing high-end graphics and video editing, in which case it's quite reasonable that the increase in bandwidth that 8x provides could significantly improve performance. Remember: games are specifically tuned so that most of the textures remain on the card for significant amounts of time. For example, they design the levels so that at any given position all of the textures necessary to render the surrounding environment and any additional features (characters, weapons, effects, overlays, etc...) will fit in VRAM. However, if you're using a 3d modelling package to create arbitrarily complex environments you can quite easily exceed the VRAM on your card for a single render. At this point bandwith is key, and it is these kinds of situations where specifically-designed graphics workstations (eg. SGI) mop the floor with your $400 games cards.

No luck yet for AMD-based solutions

[ez76]

By all accounts, development of SMP motherboards for Athlon has all but stopped pending the release of the next generation of Athlon MP ("Barton").

This is largely due to the fact that as of late last year, Intel multiprocessing solutions have become cheaper than their AMD counterparts. Intel has reduced lower-end Xeon pricing as faster Xeons have come out. AMD has not done the same with Athlon MP prices. And so Tyan, MSI, Asus et al. are not spending much time thinking about how to keep their Athlon MP motherboard line up to date.

This is just a guess, but it might also have something to do with some bad blood between AMD and manufacturers: the most recent AMD chipset for dual Athlon MP's (760MPX-based) had a bug in the Southbridge that completely disabled on-board USB 1.1 (oops) and it took AMD a while to get a fix into production motherboards. That probably didn't earn them big points.

agp 8x mainboard...

[joelja]

currently your only choice that meets both of your criterion (agp 8x and dual cpu support) is the intel 37505 chipset. that meens of course you'll be shopping for socket 603 xeons...

I would expect in most application benchmarks you'll see the difference in benchmarks of agp 4x and 8x being vanishingly close to zero at this time but yuor mileage may vary, especially if you're a doom3 developer... ;)

Anyway supermicro makes such a board, the super X5DAL-TG which also has serial ata and gigabit ethernet so it's probably a niceish board even if it's outside my price range...