2900 Crossfire...

[J0hnb0y]

These cards are big power consumers so i was wondering if my Thermaltake Toughpower 550W could power them. It has 2 PCI-E connectors the are presently in my 2900 so the other would need 2 molex -> PCI-E connectors.

I'm not sure it will have enough juice tbh as these cards are power hungry and if i need a new PSU (expensive 1...!) then a second Pro doesnt seem worth it

opinions?!

 

[paradigm]

No, I'd hazard a guess that a 550W won't be enough.

 

[J0hnb0y]

bugger!
thought so. instinct tells me to pick up a cheap 2900 pro off MM...but i might just *try* and sell my 2900 and get 3870...

how much juice for x2 3870's?

actually on second thoughts a GT is a better buy unless i already have support for xfire eg. PSU + cards

 

[paradigm]

I'm running two 3870's on an Antec 550W

 

[Scougar]

Unless your planning on overclocking the 3870's I reckon getting 2x 3850's is a much better idea. (cheaper and take less to power).

Matthew

 

[paradigm]

Unless your planning on overclocking the 3870's I reckon getting 2x 3850's is a much better idea. (cheaper and take less to power).

Matthew

That makes no sense

Surely, if you plan on not overclocking, you want the best starting point you can get. They also (the 3850's) don't need that much less power, and given that he has a 550W PSU anyway, he already has enough juice for the 3870's.

 

[J0hnb0y]

Unless your planning on overclocking the 3870's I reckon getting 2x 3850's is a much better idea. (cheaper and take less to power).

Matthew

Could you elaborate on this please?!
Are you saying that 2 overclocked 3850's is better than 2 stock 3870's? But then overclcoked 3870's<3850's...?

 

[paradigm]

Basically what he is saying is wrong.

If you are staying at stock, then 3870's (whilst costing £20-30 more per card) are faster than 3850's (You need 512MB 3850's for crossfire to be worthwhile).

If you are overclocking, then the GDDR3 of the 3850's will hold you back, and the GDDR4 of the 3870's clocks a LONG way most of the time (mine are at 1350MHz / 2700MHz DDR).

For the price difference, the 3870's are far far better suited to crossfire tbh.

 

[J0hnb0y]

well that's what i thought particularly as i am running a 2900XT (clocked Pro) and would like to see a performance increase without so much noise + heat!

I may flash the Pro to XT and send it to the bay...unless anybody on here wants a rather expensive 2900XT clone?!

hehe i thought not. cheers for the advice

 

[Fothsn]

Get the 3870 I did and I'm more than happy if you can live with the noise I couldn’t as I sometimes run Vista MCE on my main machine and the fans on the 2900XT were well loud to say the least, the 3870 doesn’t have this problem coupled with far lower power requirements it’s a winner, if you can sell yours and get one with in £20 I would go for it.

 

[gt_junkie]

My 2900XT crossfire rig was run off a toughpower 850 and still worried me a little as the cards wouldn't clock that well - i had a couple of instability issues but it was fast!

As others have mentioned the 3870's would be a worthwhile move. I downgraded from the 2900xt's in crossfire to the single 3850 in my sig. The performance drop is not actually that much. I'd say my single 3850 clocked to 770/999 is around as fast as a stock 2900XT.

I game @ 1920x1200 by the way.

gt