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One 5770 @ Higher Clocks vs XFire 5770 @ Lower Clocks

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June 3, 2011 5:23:01 PM

Hi!

I've recently stumbled upon this dilemma...
Right now I am running two 5770 Hawks in crossfire with slightly overclocked speeds 975/1300.
I would've loved to get higher clocks as others have done, i.e. 1000+/1400+ (with a single hawk).
However, strangly enough, when crossfire is enabled, I am unable to change the core voltage from its stock value @ 1.200V.
I am using MSI Afterburner to tweak my overclock and MSI Kombustor to stress the cards.


So my main question is:

Should I maintain the crossfire setup with slightly slower clocks VS should I go with one hawk and raise the voltage, which would allow me to overclock further? Would the higher overclock of a single hawk yield better results opposed to the crossfire of only slightly overclocked hawks?


Hope this is all clear ^^
Thanks in advance~
a c 125 U Graphics card
a c 100 K Overclocking
June 3, 2011 5:44:15 PM

Hi,

First off, what do you mean by you're unable to change the voltage? Does it have an error when you try, or is it completely unavailable?

Secondly, as far as I know (from personal experience) MSI Kombustor doesn't work with crossfire - it only stresses a single card. Although, if you see max usage on both cards then I guess it works for you, but the last time I tried with my 5850s it wasn't working properly. I use FurMark instead.

Finally, there's no way a single, highly overclocked card will compare to crossfire even if you underclocked them. The FPS boost for overclocking is maybe... 5fps let's say. Adding the second card is up to 90% faster, so as much as 30 or 40 more fps.

You can test this out easily enough, just disable crossfire and run a game.
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June 3, 2011 6:00:42 PM

Thanks for quick reply Wolfram23!

Quote:
First off, what do you mean by you're unable to change the voltage? Does it have an error when you try, or is it completely unavailable?

No, there's no error. It's just I set it to 1.3V in afterburner and it shows 1.299V in Afterburner, which is fine, but when I load up GPU-Z and check the voltage, it still shows 1.200V as if nothing changed. Unless of course, GPU-Z does not show the higher voltage changes...(I highly doubt that)
Also I read somewhere that Afterburner does not support overvoltage if the cards are in crossfire, only possible for single cards...

Quote:
Secondly, as far as I know (from personal experience) MSI Kombustor doesn't work with crossfire - it only stresses a single card.

No, it stresses both cards fine. Maybe this issue was fixed in the newest version (2.10)

Also, it's not that I 'underclocked' them in crossfire. I just have them overclocked less than what a single hawk is capable of being overclocked to. (Probably what you meant, but just clarifying~)

Anyway, you're saying that even a slightly overclocked crossfire is much better than a highly overclocked single card?
If so, case closed. lol
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a c 125 U Graphics card
a c 100 K Overclocking
June 3, 2011 7:33:15 PM

Yeah that's what I'm saying.

But... if Afterburner is showing the higher voltage then it's most likely working. An easy test is to run the same clocks with different voltages and see if the temps are higher. Be careful though... you should only increase voltage if you need to. "Highest clocks" are extremely flakey, as all cards will have their own limits. But anyway, you definitely can set different voltages with Afterburner and crossfire. I've done it lots.
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June 3, 2011 9:06:26 PM

Well I've been testing it out all day, and seems to me that the Voltage does change, cause I'm not able to maintain the higher clocks when I dropped the voltage back down to stock in Afterburner. So, I'm concluding that GPU-Z only shows stock clocks, even if it is higher in Afterburner.
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!