Originally Posted by magbarn
Tachikoma he is part right. My 9300 if I use the 9300 bios with my 7800GTX, will not recognize my vid card correctly. In the cmos it says "unknown video card". Even though I have a 130watt brick and 9 cell battery installed the vid card always runs in low power mode. I can't get higher than mid 3000's in 3dmark05. Once I reflash the bios to XPS2 the GTX then kicks into higher power mode and I then get around 6800 in 3dmark05. This is exact same install and drivers. Only difference is between having the XPS2 bios and the 9300 standard bios. So the XPS2 bios is required to get the vid card to request the extra power from the 130w power supply. You 9400 users are lucky that your own standard bios recognizes the 7800gtx. Hope your new card works. The voltage regulators are the same on the 9300 and xps2 though.
Personally, the i9300 BIOS wasn't written as well as it should've been. There was really no reason for Dell not to include the instructions for the 6800 Ultra, at least. I can understand not having 7 series support (since it wasn't out yet, hehe). But no 6800Ultra? C'mon.
Anyways, here's how it works. With the base i9300 BIOS, it doesn't know what card is installed (6800Ultra or 7 series). It draws the basic amount of power it needs to function, hence the low power mode. The video card can't draw more from the brick because the BIOS doesn't know what instructions to give it. Does that make sense? I'm not trying to be an ass here, just explaining. So yes, I suppose in a sense it's the BIOS's fault it isn't getting propper power. But the BIOS doesn't determine what power to give what device, it acts as a "middle man," in a sense.
The e1705 is completely different. It recognizes the card right off the bat. Hence, it will/should know what commands to give the card. Since it knows what commands to give the card (support for the 24 pipelines and speed of core/mem/etc) the video card "asks" for the appropriate amount of power. Now as the other user who's done the mod has stated, when he plugged in his 90w brick, it didn't work, because it couldn't give the juice the card needed. This tells us that the BIOS does know what instructions to give the card, so when the card is fully functional, it's going to "ask" for the propper amount of power it needs, hence the need for the 130w brick.
Anyways, hope that clears it up a little bit more.