• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

3.3V AGP

VIA's Web site says that both the KT333 and KT400 support AGP 4X and 2X...but does anybody know of any motherboards that will allow the use of an AGP 2X 3.3V card?
 
Only Intel's AGP 4x chipsets aren't backward compatible. Everyone else's are. AGP 1x/2x cards always use 3.3V signalling, so if a mainboard has a "universal" AGP slot, it is able to run them.

regards, Peter
 
Peter,

SiS' web site doesn't say that the 648 is compatible with 2X.

nVidia's web site doesn't say that nForce (1 or 2) is compatible with 2X.

Likewise, as you mentioned, Intel's site doesn't say that its P4 chipsets are compatible with 2X.

This leads me to believe that these chipsets do not support 3.3V cards. Especially since I'm not aware of any boards based on these chipsets which support 3.3V.

In any case, I'm referring specifically to KT333 and KT400. According to VIA's site, these chipsets are compatible with 2X. However, chipset compatibility doesn't guarantee that a particular motherboard will work with a 3.3V card. It depends on the type of slot used on the motherboard, as you alluded to.

My question was: which KT333 or KT400 motherboards (not chipsets) will support a 3.3V card?

I know that AOpen's KT333 and KT400 boards are keyed for 1.5V. This is also the case with Asus' A7V8X and (I think) their A7V333.

But what about other boards?

I was hoping that owners of KT333 or KT400 boards would sound off with regards to their particular boards.
 
Keep supply voltage (mainboard dependent) and signalling voltage apart. The latter is what the chipset must support - and the supply voltage is ALWAYS 3.3V anyway.

SiS 648 feature list says 4x backward compatible only, so they might follow the Intel 845 route of removing 3.3V signalling support for 1x/2x AGP - or they were just being brief while writing that list. Its Athlon sibling 746 is listed as 8x/4x/2x.

VIA's current chipsets dropped 1x support only, 2x is still there according to their site.

 
AOpen has a picture of their AK77-333 (KT333) board. The picture shows a universal AGP slot:

http://club.aopen.com.tw/pss/largeview.asp?modelname=AK77-333&img=http://www.aopen.com/products/mb/images/ak77-333-b.jpg

However, their manual for this board clearly states "this AGP expansion slot is for is for 1.5V AGP card only."

This is why I'm not so sure that a board with a universal slot will always work with a 3.3V card.

With regards to signalling voltage, isn't this also board dependent? For example, a KT266A board with a slot keyed for 1.5V cards would not work with a 3.3V card, right?
 
Peter, BTW, in your last post, you say that supply voltage is mainboard dependent, but then you go on to say that it is always 3.3V. Would you explain? Thanks.
 
What I was trying to say is that the AGP supply voltage is something the mainboard designers must take care of, with not too many possibilities of screwing it up since there is only one voltage to support.
 
Ah, OK, that makes sense.

Would you care to address the AOpen KT333 board having a universal AGP slot but apparently not supporting 3.3V cards?
 
Umm ... well if they populate a "universal" slot hardware there, the thing should be supporting 2x/1x cards. If it doesn't, then there is a screwup somewhere.

Most Intel 845 based boards have it right, with the AGP slot having the 4x-only key. I'd talk to AOpen about this.
 
Asus' P4S8X also has a universal slot but doesn't support a 3.3V card. In fact, there is a warning light that comes on should a 3.3V card be inserted, and the board will refuse to boot.

So far, what you're telling me doesn't jive with what I'm seeing/hearing elsewhere.
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top