G400's and 4x AGP

[Dyre]

Just a question for the experts. I have heard that the G400 series is 4x(sideband) compatible, but i was wondering if it will accually take advantage of the 4x speeds. Or is it just saying that it will run on a 4x AGP bus, but will still only be transfering at 2x(sideband). If it can run at tru 4x speeds that would be great, it should really speed things up with larger textures.

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</list>
PIII 450 @ 464
generic BX6 motherboard
G400 MAX : )
Maxtor 13 gig UDMA 33
Maxtor 13 gig UDMA 66
Creative 36x CD-ROM
HP 2x2x6x CD-RW
64 megs PC100 RAM
Intel 10/100
Soundblaster 32 AWE
DiamondMAX 56k
Logitech Wireless Desktop (best $50 ive ever spent)
4 large fans.

[Nuno]

Being AGP 4x compatible, that only means it will work in a AGP 4x slot, but will only do 2x transfers. That makes sense, when the G400 boards were designed, the 4x specs were hardly known.

huh... what larger textures? There isn´t hardly a game wich uses AGP nowadays (let´s all thank 3dfx and it´s old crappy hardware and the people who are buying it, retarding the game developing por several years just to be compatible with the large amount of non-agp non-32 bit non-large textures boards around), much less AGP 2x or 4x. You can only tell the diference in synthetical benchmarks.

[Dyre]

Ive seen some stuff on a GeForce DDR that supported larger textures. I think it was the beta Full version of UT that let you use like 1600x1600 textures instead of the standard 256x256 textures currently in use.

Thanx for answering though, thats what i thought. Just like 8x compataible cd-r's there no better, they just work in 8x. Its kinda bullshit.

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</list>
PIII 450 @ 464
generic BX6 motherboard
G400 MAX : )
Maxtor 13 gig UDMA 33
Maxtor 13 gig UDMA 66
Creative 36x CD-ROM
HP 2x2x6x CD-RW
64 megs PC100 RAM
Intel 10/100
Soundblaster 32 AWE
DiamondMAX 56k
Logitech Wireless Desktop (best $50 ive ever spent)
4 large fans.

[The Rock]

Correct me if I'm wrong, but doesn't the G400 support up to 2048x2048 texture size?

The Rock

[Ashley]

The AGP 2.0 specs were released in May 1998, so the argument that AGP 4x was unknown when the G400 was designed doesn't hold much water...

In any case, it appears that the G400 chip itself can support 4x transfers, but not fast writes. The G400 *cards*, however - and that's all that really matters, isn't it? - cannot do 4x transfers, even with a BIOS update, because they've tied the typedetN pin on the card to 1.

It seems like a jumper on the card to let the user select between 1.5V AGP and 3.3V AGP would have resolved this issue. The only reason I can think of for Matrox not to do that is the obvious marketing one of planned obsolescence.

[Rags]

Ashley,

Actually I believe the G400 *Will* run with 1.6V AGP slots (AGP 2.0 slots), it auto detects the slot it's in and adjusts accordingly. If it was any other way, it would NOT work in AGP 2.0 slots that are low voltage only. Maybe Haig can answer this for sure, but I remember him saying something about this.

BTW there are AGP 2.0 low voltage slots available on motherboards that do 2X max. Just because a motherboard is AGP 2.0 low voltage, doesn't mean it is a 4X board.

Rags

[Ashley]

Rags - it would be good if that were the case, and hopefully it is. It'd be nice if Matrox would clarify this officially.

In the G400 *chip* specs, though, the two issues (support for 4x transfers and low voltage) are tied together by the state of just one pin, and I wouldn't be surprised to see a new G400-based card from Matrox that specifically supports AGP 4x transfers.

[Nuno]

Rags: I clearly remember Haig stating that the G400 was the only card in its current generation to automatically support the AGP 4x slot, detecting it and autoswitching the voltage. *some* TNT2 have this ability also, but a jumper must be configured in the card.

Ashley: AGP 4x specs could be out when G400 was *released* but I bet that back in May 98 the G400 chip design should be near completion, or maybe even alpha or beta silicon in testing. Just guessing here, but by that time a major redesign of the chip to suport a standard that the G400 may not even outlive would be totally out of question. Not mentioning that there wasn´t a real hardware platform suporting AGP 4x, so where would be the 4x compatibility tests be conducted?

[Dyre]

Damn interesting. These are the same questions ive been throughing around in my head. thats why i posted the question, to get some clarification. LOL


------------------
</list>
PIII 450 @ 464
generic BX6 motherboard
G400 MAX : )
Maxtor 13 gig UDMA 33
Maxtor 13 gig UDMA 66
Creative 36x CD-ROM
HP 2x2x6x CD-RW
64 megs PC100 RAM
Intel 10/100
Soundblaster 32 AWE
DiamondMAX 56k
Logitech Wireless Desktop (best $50 ive ever spent)
4 large fans.

[Haig]

The G400 will support a 4x motherboard by auto switching the voltage when it detects a 4x slot. Even then, we will do 2x transfers.

Ashley, maybe it doesn't hold water for you but claiming to support 4x transfers because of a spec released over a year ago for a future technology would be suicide don't you think?

Especially when no motherboards were available to even test. The AGP2 specs were still being revised when the G400 was officially released.

The only item that wasn't revised were the 2x/4x notches on the card's connector.

If you really believe that date has the finalized spec, then it's been 18 months, but where are the motherboards?

Haig

[Ashley]

Haig - I appreciate the dilemna, and as a Matrox customer I don't personally feel mislead about this issue at all. But you guys are partially responsible for the confusion. In fact, it seems to me Matrox has actually milked the fact that "AGP 4X" can refer to several things, when you're surely aware that most people take it to mean 4x transfers.

Just do a search on Matrox's site for "4x", and you'll find plenty of references to the G400 ("a fully optimized AGP 4X chip" - that's from a 3/99 press release, btw, long before the card shipped). And though there's the oft-repeated distinction between the G400 card and the G400 chip, Matrox happily quotes reviews that claim the G400 *card* "has full support for both AGP 2X and 4X".

After all, if there was no remaining ambiquity then the question that started this thread wouldn't keep coming up again and again...

[Nuno]

See, I told you

[Haig]

Hi Ashley,

I can see why the confusion. Most people don't realize that there is a chip spec and a board spec. Combine that with the term "support 4x motherboards" and the fact that the chip specs are released before the board specs, some folks will have the impression that we do 4x transfers.

In any case, when clients emailed or phoned Technical Support about this, we always gave our clients a simple answer when asked if we do 4x transfers.

Haig