"2x/4x graphics-card" is a confusing but common term for a card that fits mechanically into a mainboard with an AGP 2x slot or alternatively with an AGP 4x slot but supports either (2x and 4x-) or 2x-only-mode. The electrical difference between both types of "2x/4x graphics-cards" (Matrox G400 is a well-known example for both types depending on the manufacturing date) is having a _1.5V-signalling_mode or not. 4x-mode _requires_ for functioning on any mainboard a 1.5V signalling-mode of the graphics-card, 3.3V or 1.5V are alternative signallings for 2x-mode, according to AGP 2.0 specs.
_Any_ 2x/4x graphics-card that has a 1.5V signalling mode must indicate this to the mainboard by a hardwired connection between the TYPEDET# pin and GROUND of its AGP-connector. A card that has no 1.5V signalling must leave the TYPEDET# pin open (unconnected to anything).
The problem with some of the motherboards which support only 1.5V AGP-signalling is that they don't reckognize the fact that an inserted 2x/4x-card only supports 3.3V and therefore are not protected from damage by powering on the pc with the card inserted.
To be sure that it's safe to insert your 2x/4x card into your 1.5V siganlling motherboard you can simply measure the resistance between TYPEDET# and GROUND with an Ohm-Meter.
The physical position of the TYPEDET# pin (and GROUND pins) on an AGP card can be found in the AGP 2.0 specification.
Knowing nothing of the above ... I had inserted an old non-1.5V G400 into my new AGP-1.5V-only-motherboard. Happily the mainboard (ASUS P4PE) has an LED which, when on, indicates "this is the wrong card" - and inhibits the power-on of the pc completely when trying to boot.
-Joachim
Anne Wilson wrote:
A Soltek board, just bought, says that using a 2x graphics board will fry the mobo (wrong voltage). The G-Force2 MX-400 is a 2x/4x board. Is it safe to assume that it will have the right voltage, merely falling back to 2x if the mobo doesn't have the later standard agp?
Anne
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