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Author Topic: Why is 6970 slower than 5870?  (Read 5559 times)
Saturn7
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May 13, 2011, 03:18:21 PM
 #1

I just upgraded my card from a 5870 to 6970 and I am getting 30Mhash/sec less

The 6970 also uses more power, hotter temps and is clocked higher, what gives?
On all the benchmarks I have seen (3D Mark etc..) 90% of the time the 6970 was about 10% faster than the 5870.

On my 5870 with no hacking I get 360Mhas/sec out of the box (W7 64bit Phoenix Miner)
On my 6970 with overclocking (950Mhz) I get 330Mhash/sec (W7 64bit Phoenix Miner)

With a 5870 mining, my system was using 380 watts,
With a 6970 mining, my system is using 409 watts

With higher temps, clock speed & power usage I would be annoyed if I got the same performance, but less?

Is this a software issue, is the code not yet optimized for the 6970?


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icaci
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May 13, 2011, 04:03:19 PM
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5870 and 6970 are architecturally different. 5870 is VLIW5 (5 stream processors programmed in a single word) and has 1600 stream processors (SPs). 6970 uses the simpler VLIW4 architecture to improve SPs utilisation for mainstream gaming and has only 1536 SPs. The simpler architecture makes 6970 faster than 5870 on gaming tests. But Bitcoin mining is a completely different story. It is highly parallel and can max out the VLIW5 of 5870 thus making it faster than 6970 on equal clock speeds. 5870 is also more power efficient since it contains less transistors than 6970.

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Saturn7
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May 13, 2011, 04:13:39 PM
 #3

lol great, i could have bought two 5870 off of ebay for the price i paid for this 6970.

Well I hope Crysis 2 plays better.... Grin

First there was Fire, then Electricity, and now Bitcoins Wink
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May 13, 2011, 04:19:18 PM
 #4

5870 and 6970 are architecturally different. 5870 is VLIW5 (5 stream processors programmed in a single word) and has 1600 stream processors (SPs). 6970 uses the simpler VLIW4 architecture to improve SPs utilisation for mainstream gaming and has only 1536 SPs. The simpler architecture makes 6970 faster than 5870 on gaming tests. But Bitcoin mining is a completely different story. It is highly parallel and can max out the VLIW5 of 5870 thus making it faster than 6970 on equal clock speeds. 5870 is also more power efficient since it contains less transistors than 6970.

Your first post? What an amazing first post to the forums!  Sure beats the "Bitcoin is doomed since you guys never thought of people copying their wallets to 2 computers" variety.

Companies claiming they got hacked and lost your coins sounds like fraud so perfect it could be called fashionable.  I never believe them.  If I ever experience the misfortune of a real intrusion, I declare I have been honest about the way I have managed the keys in Casascius Coins.  I maintain no ability to recover or reproduce the keys, not even under limitless duress or total intrusion.  Remember that trusting strangers with your coins without any recourse is, as a matter of principle, not a best practice.  Don't keep coins online. Use paper wallets instead.
Xenland
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May 15, 2011, 09:23:40 PM
 #5

5870 and 6970 are architecturally different. 5870 is VLIW5 (5 stream processors programmed in a single word) and has 1600 stream processors (SPs). 6970 uses the simpler VLIW4 architecture to improve SPs utilisation for mainstream gaming and has only 1536 SPs. The simpler architecture makes 6970 faster than 5870 on gaming tests. But Bitcoin mining is a completely different story. It is highly parallel and can max out the VLIW5 of 5870 thus making it faster than 6970 on equal clock speeds. 5870 is also more power efficient since it contains less transistors than 6970.

Your first post? What an amazing first post to the forums!  Sure beats the "Bitcoin is doomed since you guys never thought of people copying their wallets to 2 computers" variety.

Not to get off topic but is that possible? And A follow up question i guess is did they think they could double spend if they did that or something? Becuase that just sounds rediculas.

To the OP, i would have checked the hardware comparisan chart before buying but too late now. Im thinking about just getting another 5670 so i can have them both run my games abd mining faster. Cant wait til the high end cards start to lower in price.
Saturn7
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May 29, 2011, 03:09:47 PM
 #6

Okay, after playing with setting for a week I now have a stable config that wont crash my 6970 and will give a decent mhash.

WORKSIZE must be 128 for the 6970.

6970 worksize 256 = 330 Mhash @900Mhz
6970 worksize 128 = 380 Mhash @900Mhz

Aggression over 9 will cause overheat.

Can safely over-clock to 930 Mhz, this will give a hash rate of 400M/hash with memory at 900Mhz. Lowering memory below 900 on my system causes it to lock up if I use the system.

Temps stable at 80C but fans at 100%

Power Control Settings: 10%

First there was Fire, then Electricity, and now Bitcoins Wink
grue
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May 29, 2011, 03:41:35 PM
 #7

Power Control Settings: 10%
whatt??

It is pitch black. You are likely to be eaten by a grue.

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Saturn7
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May 29, 2011, 04:18:07 PM
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Power Control Settings: 10%
whatt??

In Catalyst Control Center 11.5 voltage is controlled by a slider in the overdrive menu called Power Control Settings.
So 10% is 10% more than stock voltage.

First there was Fire, then Electricity, and now Bitcoins Wink
grue
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May 29, 2011, 06:14:53 PM
 #9

Power Control Settings: 10%
whatt??

In Catalyst Control Center 11.5 voltage is controlled by a slider in the overdrive menu called Power Control Settings.
So 10% is 10% more than stock voltage.
oh. i thought you were using 10% of the stock voltage.

It is pitch black. You are likely to be eaten by a grue.

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