AGP X8 backward compatible?

I have an older PC which supports video AGP X4 maximum.
I have just purchased a new video card however the sellet sent me the wrong video card.
The video card (GeForce FX5500) only mentioned AGP X 8.
The seller reckons that it would be backwards compatible and would work on 4 X.
I am not sure and seem to remember that if you use X 8 on a motherboard which supports X 4 only that you can cause damage (as the voltages are different).
Can anyone shed some light on this for me and assure me that video cards are backwards compatible - I don't want to damage an expensive video card (or my motherboard).
Thanks
John

 

This is testing my memory JP!

There was a voltage difference between AGP 2X upwards. I THINK some of the early 4X AGP cards worked on a different voltage to latter versions.

I think you will find that the card is keyed differently if it is a different voltage. Keyed means that the card will not physically fit into the slot. There should be different keys for different voltages (for 4X).

The motherboard may handle 4X maximum. The graphics card should be backwards compatible.

Look at the connector keys on the card. If they match with the keys on the motherboard, they should be compatible.

To be certain...
Look up the voltage used by both , look at the specifications (or websearch )

[Rockster2U knows about this, hope he is overcoming any problems (hurricane Gustav)]

Matt

 

AGP8 is 1.5 Volt only, most AGP8 cards are suitable for both 8 & 4 unless it is a really old board. It will always warn you to make sure it is 1.5 Volt.
Like Matt has pointed out if it is keyed correctly it is almost certain that it is ok. Only problem that can occur is that your power supply might not be up to it AGP8 will use more power, so you will have to keep a lookout for that.
If you have a manual for your motherboard it will most likely state AGP 4 & 8.
hawk22

 

Thanks everyone for your replies.
I decided to return the video card purchased even though I found that it would work on a AGP X4 motherboard. I found this cia an excellent article in Wikipedia
http://en.wikipedia.org/wiki/Accelerated_Graphics_Port

I had ordered a Radeon 9600 XT (listed as 4X/8X) and they incorrectly sent me a GeForce FX5500 (listed as 8X). The seller reckoned the GeForce is a better card (what does everyone think of this statement?) however but I wanted a card which would support pixel shading 2.0 (for a new game given to me for a recent birthday) and I could not find if the GeForce card did.
It seems (according to the WikiPedia article) that most 8X cards are backwards compatible.
I urge you all to view the WikiPedia article (see above) as it is very interesting.