Hi All,
From what I have been able to find and using other related info I have come up with this guess on the 7990's. Please tell me how and why you think these numbers could be improved.
Will be released in March.
Will cost $800.
Will hash at 1.2G.
Will use 300 watts.
(slight undervolt, mem down clock to 300 and the core at 1100)
Thanks.
Umm .. no ... not quite.
Will be released between March and April, but only after all other offerings, i.e. 7770, etc.
Will cost $849, list ... there will be an immediate shortage and you will see street prices for $999 ... eBay listings will have them for $1100-$1200.
Will hash at 975 mhash/sec @ 820 mhz, if overclocked we will be lucky to see 1100 mhash/sec @ 925 mhz.
Will use 375 watts.
Here is the reason ... currently the 7990 has a power problem. The power demands of the 7970 are greater than a 6970, but a 6990 was basically a underclocked dual 6970 and was maxed out on power. Very little overclocking room before saturating the available 375 watts. The 6990 allowed raising the voltage and bumping power up to 420 watts but this was beyond spec and some poorer quality molex connectors didn't survive.
Remember they don't tune these things for miners with low mem speeds and all.
So ... what we are looking at is is a power consumption of 232 watts at stock clocks/mem/voltage. So two of them would be around 464 watts. Now moving to a single fan might shave off 20 watts (30 watts tops) ... so 430 watts at stock voltage/mem/clocks... this is a problem .. that is where they want to be after overclocking.
So they will have to introduce them at a lower clock rate, perhaps 820 mhz instead of 925 mhz ... which would shave it to roughly 200 watts per gpu. Again a little fan savings... and bam ... we are at 385 watts ... damn ... still too much ... especially since the added PCI-e bridge on board uses 5-7 watts. So we are actually at close to 392 watts again ... not a lot of margin.
Plus they don't typically ship with settings that run absolutely to the bleeding edge of the spec ... they want you to be able to overclock some..
So ... what can they possibly do ... they will undervolt them stock, which will limit the ability to overclock like a 7970 to 1100-1200 mhz.
I expect them to intro closer to the 1.00-1.05 volt mark ... this would put the power about 25-50 watts less per gpu.
So .. then you are looking at;
820 mhz clock @ 1.05 volts using about 335 watts doing 975 mhash/sec
or
820 mhz clock @ 1.00 volts using about 300 watts doing the same hash rate.
Remember they want you to have plenty of room to overclock and buy ridiculous cooling hardware and publish tons of reviews, etc, etc... this is all good media for them...
