Crossfire basics question

[jhokie]

Just a couple of basic questions about crossfire:

I have an unlocked Saphire reference 6950... running 6970 bios clocks 920 - 1375 +20% power in catalyst control center. I'd like to add a second card... which will likely be a 6950 due to money, power supply and cooling issues. I currently use msi afterburner for my fan profiles and such.

1) I assume adding the 6950 will clock my unlocked 6950 down to normal levels to match it... voltage clock speed etc. Is this correct? I can just leave the bios as is on my current card?

2) If a game does not support crossfire... can I just switch to my single unlocked 6950 and use it as a 6970... or will it be downclocked to a 6950?

3) How do I manage fan profiles for multiple cards, including a profile if I'm using my single card as a 6970?

4) I think my current power supply could handle this setup, especially if I run the cards as crossfire 6950s. Thoughts?

Ok, so those questions ended up being more than basics
System info in case you need it:

2600k @ 4.4
8 gigs ram @ 1600
750W corsair modular PS 80 plus Silver
Gibabyte Z68X-UD3H-B3
HAF 922 Case
Saphire reference 6950 - 6970 bios 920/1375 +20%
Crucial SSD + 2 7200 HDs

 

[lsweet]

Probably not the answers you are looking for, but at least for #4 -- I'm running two 6870's stock on a 650W while my other supply is out for RMA, so your current supply should be fine. I figured my power usage to be around 575W which doesn't leave me much room, but it will give you an idea.

 

[jhokie]

I'm really surprised at this result... I got a Kill a Watt from a coworker. Either my power supply is super efficient, or this Kill a Watt is bad.

First I ran some games, BC2 and Metro 2033 and my power usage was maxing out at about 310 watts at the wall. I was like WTF.

So then I ran Prime95 and Furmark at the same time. Maxed out gpu and cpu utilization at the same time, and I was just hitting about 390 watts max at the wall. I may try SLI after all.