2x GTX260 build questions

[bebblebrox]

Here's what I just built:

Rosewill Xtreme Series RX850-D-B 850W

AMD Phenom II X4 965 Black Edition Deneb 3.4GHz Socket AM3 125W Quad-Core Processor Model

OCZ Platinum 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Dual Channel

COOLER MASTER HAF 922 RC-922M-KKN1-GP Black Steel + Plastic and Mesh Bezel ATX Mid Tower

MSI NF750-G55 AM3 NVIDIA nForce 750a SLI HDMI ATX AMD Motherboard

2 BFG Tech BFGEGTX260MC896OCDE GeForce GTX 260 896MB 448-bit GDDR3 PCI Express 2.0 x16

First question, is that power supply enough? It's not on nVidia's list, but no Rosewill's are. It's got enough channels and volts as near as I can tell, but I'm not 100% on that

Second question: is dual 16x required for your cards to perform at maximum capacity?? I've seen several posts/writeups that say 16x gets you very little benefit from dual 8x. Well, I ran 3dMark and scored 19500ish vs 23000ish that's on the 3dmark chart here on TomsHardware.

So basically, I'm wondering why I'm a good 4000 lower, and what I can do about it while I still have time to return things to newegg

 

[bebblebrox]

*PSU has enough rails

lol sorry too early in the morning still