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View Full Version : Im new to this stuff, is two 6800GT's better than a single 7800?


benquirkten
04-24-06, 04:35 AM
Hi im pretty new to this stuff, looking to upgrade most parts of the computer I have had for ages, and wanted to ask you guys about the graphics card.

I was thinking that having two cards would be rockin, so would two 6600gt's be better than a single 7600 or 7800 ?

I do a fair bit of 3D stuff using maya and also want to be able to play a few games on decent quality settings.

Was thinking about getting an amd 3800+ dual core if that is any help.

Thanks in advance

:D

Ben

Superfly
04-24-06, 05:31 AM
Im not sure but I'd of thought 2x6600GT's would beat a single 7600GT.

I doubt they could match a 78 though - also with 2 cards you have double the power and double the noise to worry about.......

bosco989
04-24-06, 09:03 AM
yeah this is how it would work...

2x 6600GT's > 1 7600GT

2x 7600GT's > 1 7900GT

Sparky6string
04-24-06, 09:10 AM
I'm hecka new too... and not to hijack the thread but...

So you can use two video cards at the same time? How much better is the performance? Using this example, would 2 6600's be better than 1 7900?

Superfly
04-24-06, 09:33 AM
I'm hecka new too... and not to hijack the thread but...

So you can use two video cards at the same time? How much better is the performance? Using this example, would 2 6600's be better than 1 7900?

no - 2 76's would be though.

Athena
04-24-06, 11:29 AM
From what I have read if you want a down and dirty simple way to see how fast SLI will be to a single card solution try this equation.

SLI performance: total pipes of both cards mutiplied by the core speed then multilpy again by 80 or 85% to get total performance in games.

Single card: total pipes multiplied by the cord speed.

So exemples follow:

2 6600s in SLI vs. 1 7800GT

6600 SLI performance = (16 {8 plus 8 pises per card} x 350 {speed of cores} ) x .80 = 4480 effective game performance

7800gt = 20 {pipes} x 400 {speed of core} = 8000 effective game performance.

That is just an example I do not know the core speeds for those 2 cards so you would have to look those up when you are picking which card to buy. Also some games are more than 80% effecient in SLI mode so that is also something to think about.

Last comment on ATI in crossfire mode. At this time the performence, to me, does not weem worth it unless you are at the top of the foos chain like 2 1900s or 2 1800s.

Good luck guys!! :D

Superfly
04-24-06, 11:33 AM
using that rule 2x7600GT's @ 590 core would be 11328 @ 80% effectivness.

benquirkten
04-24-06, 09:56 PM
Ok cool I have done a bit of research for anyone interested.

Using evga as an example for no particular reason, i have looked at all the specs and prices and am going to work out if its worth my while getting two older model cards as opposed to one newer one.

so starting with the slowest first and using athena's basic rule of thumb:

6600 GT SLi:
GPU 500mhz; pp's 16 (8x2) at 80% = 6,400 at $560 ($280x2)

6800 SLi:
GPU 325mhz; pp's 24 (12x2) at 80% = 6,240 at $460 ($230x2)

7600 GT CO SLi:
GPU 580mhz; pp's 24 (12x2) at 80% = 11,136 at $440 ($220x2)

7900 GT superclocked (single):
GPU 550 mhz; pp's 24 at 100% = 13, 200 at $349

So it looks like using athena's rule then getting a 7900 is the cheapest and fastest way to go..

although I was wondering, seeing as there are two gpu cores in SLi shouldn't you double the mhz like we did with the pixel pipelines? Excuse me if this is a stupid question.. if you do double the mhz then it works out for two 7600 GT's to be the best buy by miles.

So whats the go guys? Thanks for ur help so far.

SH64
04-24-06, 11:07 PM
So it looks like using athena's rule then getting a 7900 is the cheapest and fastest way to go..

You said it yourself ;)

in short SLI doubles the power "theoretically" , but in practical there are factors that reduces this like the drives compatibility , game coding etc..
from my own experiance the gain from SLI is around 50-70% in most games .. it goes beyond in "some" games which are coded very well to take advantage of SLI & its less to none in a few others.

KickAssCop
04-25-06, 12:40 AM
Get a 7900GT CO Superclock and add another one laters ;).

Anything from the 6 series should not be considered anymore.

nforcer
04-25-06, 12:47 AM
Jeez, that gave me a whole new perspective. I have a A8Ne board, think I will make full use of that and go for a 7000 series.

SLippe
04-25-06, 12:31 PM
Get a 7900GT CO Superclock and add another one laters ;).

Anything from the 6 series should not be considered anymore.
Ditto.

ViN86
04-25-06, 03:07 PM
although I was wondering, seeing as there are two gpu cores in SLi shouldn't you double the mhz like we did with the pixel pipelines? Excuse me if this is a stupid question.. if you do double the mhz then it works out for two 7600 GT's to be the best buy by miles.
no dont double the mhz. the two cards run at the same GPU speed, so those pixel pipelines are both being powered by the same amount of juice each.