I think I can answer my own question. I have found in Asus P4T manual such statement:
"The slot is keyed to support only the latest 1.5 volt AGP cards: i.e.: ASUS AGP-V3800 and newer versions."
I am going to try it out. I hope that the card will live 😀

I don't know if it will work on 1.5v boards, I would be suspicious for anything of that particular vintage, or anything before the geforce 3, as there were even a few geforce 2 cards that for some stupid reason were 3.3v only.

But, if it does not support 1.5v and is 3.3v only, it won't the the videocard that dies. The card will likely be fine, the motherboard less so. Chances are it will kill the motherboard in that case. I speak from experience here.

I would not just "test" it but rather wait until you find definitive information.

My Asus 3800 M64 card does work on both voltages, IIRC the manual for the card explains it.

According to this site, card should be universal, and should work in any AGP slot.

http://www.playtool.com/pages/agpcompat/agp.html

I think, that 0,8/1,5V only motherboards are only those with P4/C2D, but this universal card should work in those, and also in older one.

I have that exact card, and I haven't tested the card in my Socket 754 that has AGP 8x (0.8V), which is backwards compatible with AGP 4x. I tested the card with AGP 2x and 4x on my Socket 370 system that has AGP 4x (1.5V).

There isn't any 0,8V ONLY motherboard or GPU...

But there are two pieces of information which they're missing: nobody makes AGP 3.0 cards, and nobody makes AGP 3.0 motherboards. At least not any manufacturers I can find. Every single video card I could find which claimed to be an AGP 3.0 card was actually a universal 1.5V AGP 3.0 card. And every motherboard which claimed to be an AGP 3.0 motherboard turned out to be a universal 1.5V AGP 3.0 motherboard. It makes sense, if you think about it, because if anyone actually shipped a consumer-oriented product which supported only 0.8 volts, they would end up with lots of confused customers and a support nightmare. In the consumer market, you'd have to be crazy to ship a 0.8 volt only product.

Thank you for all the replies. My card finally arrived today, so I am going to test it this evening. First, I will try some older board to test if it actually works, and then - NF7. Fingers crossed 😀

Cheers @Srandista, I have almost the same build - E5700 @ 4GHz, 4CoreDual-VSTA, X850 Pro + X850XT PE (two cards, currently using Pro because it is signle slot and I need PCI-E slot below). Great platform, runs every OS nicely and X850 have better compatibility than GeForce 6 series under W98.

I think that those two pics sums it all 😀

(Please note that result had been taken using Windows XP driver and could possibly be better)

Not bad. It's cool to see a motherboard that supports AGP 4x/8x and PCI-e.

This card is awesome! Looks great and overclocks above Ultra levels (actually its possible that core could overclock higher, but I maxed out slider in PowerStrip 😀 ).