Difference between 1.5v AGP and 3.3vAGP?

StrikerNR

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Jun 22, 2003
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What is the difference between 1.5v AGP and 3.3vAGP cards?
I have the ASUS P4P800-Deluxe motherboard and it specifically says in the user guide that the motherboard only supports +1.5v AGP cards with a picture pointing to the notches on the card.

How does the a 1.5v card differ from 3.3v card?
Are ATI's 9500, 9600, 9700 series cards AGP 1.5v?
 

TheMASK

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here are the standards for the AGP cards:

AGP 2X uses 3.3V
AGP 4X uses 1.5V
AGP 8X uses 0.8V
All the cards u have mentioned are 8X cards and thus safe to be used in that mobo of yours.
EDIT: If u want to read more on this, then <A HREF="http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=356717#356717" target="_new"> READ THIS THREAD</A>, <A HREF="http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=347939#347939" target="_new"> THIS THREAD</A> and <A HREF="http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=341616#341616" target="_new">THIS THREAD</A>

<b><font color=red>The statement below is True.</font color=red>
<A HREF="http://service.futuremark.com/compare?2k3=959979" target="_new">3DMark 03 score - 297 </A> :cool:
<font color=blue> The statement above is false.</font color=blue></b><P ID="edit"><FONT SIZE=-1><EM>Edited by TheMask on 07/04/03 02:18 AM.</EM></FONT></P>
 

StrikerNR

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thanks TheMask.

Since my motherboard can only support +1.5v AGP cards and at the same time it has AGP 8x slot but AGP 8x is 0.8v (according to the threads).
This begs a question, how is this possible? Unless some AGP 8x cards are 1.5v.
If the above is possible, how does one knows if the AGP8x card is 1.5v or 0.8v. You don't see this in the specs of a card anywhere.
 

Crashman

Polypheme
Former Staff
All current AGP8x cards are AGP4x compatable. Most are also AGP2x compatable. Now, your board MIGHT only support AGP 1.5v but:

1.) AGP specs 1.0, 2.0, 3.0 are mostly signal voltage specs
2.) AGP 2x, 4x, 8x are signal multiplication specs
3.) While AGP 1.0 is for AGP2x, 2.0 for 4x, and 3.0 for 8x, boards can run different voltage signals for different speeds.

For example, AGP4x was introduced with AGP 2.0. But some cheap AGP4x cards didn't meet the voltage spec for AGP2.0, outputting 3.3v signals instead. They still operated at AGP4x, even though they weren't AGP2.0 compliant.

So basically you can run AGP8x transfers on 1.5v signals. As I stated, all current cards are backwards compatable to earlier standards.

<font color=blue>Watts mean squat if you don't have quality!</font color=blue>
 

Crashman

Polypheme
Former Staff
I believe the board supports both 1.5v and 0.8v standards, and that the warning was made to prevent people from attempting to use older 3.3v cards. But even if the board forces 1.5v on your card, you can still get AGP8x transfers, because 8x transfers and 0.8v signals are separate parts of the AGP 3.0 standard, and all these cards also support AGP 2.0.

<font color=blue>Watts mean squat if you don't have quality!</font color=blue>