AGP 2x/4x and G400 BIOS

[Snake-Eyes]

Is the current 2x limitation on the G400 series something that a BIOS update might change in the future? What I mean is this- current G400s are limited to 2x transfers, even on a 4x AGP bus. They're 4x compatible, so they'll work on a 4x bus, but only using 2x transfers, as it now stands. Is this limitation due to something in the BIOS, or is it something more permanent, like something hardwired?

It'll suck to see that I have to buy another G400Max just to get true 4x transfers (once I get a capable motherboard, that is), if it [b]is[/i] hardwired, and not just a matter of flashing a newer BIOS revision. Does anyone know the answer to this one? (Haig, maybe?)

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Ace

[Kruzin]

The current boards are 2x transfer only. Most likely there is nothing that will change that.

Even so, there will be no reason to get a different board if/when they put out a true 4x model just because of 4x. Apps of today (and the next year or so) barely use AGP 1x, much less maxing out 2x. 4x AGP is a buzzword, meant to make you do exactly what you are talking about....running out and getting the next board. While I'm sure there will be reasons to get the next board, 4x transfers should not be a high priority on anyone's list...

[Snake-Eyes]

Thanks for the input Kruzin. I understand what you're saying, but I've just been wondering if faster AGP tranfers would benefit the problem Matrox seems to have with texture management by allowing the textures to be transferred more quickly to the card when requested. If so, then AGP 4x might be a desirable feature on the G400 series, when available.

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Ace

[Ashley]

All 4x transfers really mean is that 16 bytes can be transferred in a single cycle, as opposed to just 8 bytes during 2x transfers. If 4x transfers are enabled, but only 8 bytes of data are being requested, bandwidth is being wasted - 16 bytes are transferred but only 8 bytes contain valid data. That's why 4x transfers are never going to be twice as fast as 2x transfers, any more than 2x transfers are twice as fast as 1x transfers.

But that doesn't mean 4x is just a "buzzword" - it is still better to be able to transfer 16 bytes per cycle than just 8.

[Rags]

Ace,

With 32Mb of onboard memory I dare to say that there are few apps/games out there right now that go to using all of that space up. Texture management has absolutely nothing to do with AGP transfers or its corresponding speed.

Rags

[kelin]

From what I have read/discussed the AGP 4X utilization (as opposed to compatability) is in the chip...and there is probably nothing that the big Mat can do to change that in my Max...have to go to the next gen card for actual AGP 4X...BUT...realizing that most games aren't really using 2X effectively, I would worry about it yet....should be enough (fo now) that the G400s are 4X compatable...
Kelin

[birdy]

i think the AGP 4x compatible thing that they put in the specs is just there to pad out a bit of empty space. Has anyone bought a 2x agp board and not been able to run an older 1x agp card? Of course not (i hope i'm not talking male gonads here) no mainboard manufacturer is going to build a board with out backwards support for the graphics cards that 99% of the people buying it will have. If you have a choice would you buy a 4x board and have to get a new graphics card or a 2x/4x board that you can use your current card with? As for wether the 4x gives any more benefit to the average geezer i doubt that when we have 128mb@300mhz graphics cards we'll bother much about the 512mb of system ram running @ 133 or 200. The only real benefit of the agp bus as far as i can see would be the nice shiny pci slot that it frees up. Could anyone tell wether they were using the agp or pci version of a graphics card without taking the cover off?

[Snake-Eyes]

Actually Kelin, that's the reason I posted this question. According to the stuff I've read on Matrox's site, the chip *does* support AGP 4x transfers (not compatibility), but the current crop of cards don't use it. It makes it sound as if either something in the BIOS, or else something else on the card(besides the G400 chip itself) is limiting the card's capability to 2x.

Supposedly they'll remove this restriction on future cards after true 4x motherboards/chipsets are on the market. That's why I wanted to know if it was something that a simple BIOS update could change on the current cards, or if it's something else entirely, so that there's never going to be a chance of this card utilizing 4x transfers.

I DO know that the Matrox G400 chip has the capability to do 4x transfers. Just not what is limiting it to 2x in the current run (other than the obvious fact that there aren't any 4x mobo's yet).

Thanks for the replies guys.

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Ace

[Snake-Eyes]

I forgot to add one other thing to my last reply- I understand that most games don't use 32MB textures, but it doesn't take much to use more memory than is available on-card. Especially if you're running resolutions of 1024x768 or greater in 32bit color. The frame buffer takes up memory space on the card too. Without calculating the storage requirements (I'll leave that to the web sites that've already done this in the recent past), a game like Q3Arena, running with all options high at 32bit color and textures can (and does) exceed the amount of memory available on the card.

This is the reason why my Max, while running most areas of the maps in Q3Test1.08 just fine with those settings, had the annoying habit of stuttering when facing certain walls in the Q3test1 and the tourney map. Those areas used larger textures than normal, and with memory already filled with textures from the rest of the map, the new textures had to be loaded from memory. To add insult to injury, currently the G400 OpenGL drivers don't support AGP texturing, so we lose the extra speed benefits that it offers in this kind of situation. I'm not sure this applies to the TurboGL since it seems to improve this situation greatly, ie.- even though it only shows an average improvement of 7 fps overall in Q3Demo1, it doesn't do that nasty stuttering in those certain areas.

For anyone wondering which areas I mean- two are:

1. The area in map 1 where the quad damage multiplier shows up- facing the opening to where the railgun is (with the big sword picture above it).

2. In the area at the portal (beneath where the railgun appears).

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Ace