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[m0w3r]

Off topic, but goodness 38 6970's must be loud.  I have 3 of them that whine like hell compared to Sapphire xtreme cards.

They're actually not too bad...  The box fans on the window are louder.  I'm bringing cool air into the room from an evap cooler mounted in an adjacent room.  6 of the 6970's are reference cards and the other 32 have very good coolers (MSI 6970 Lightnings).  The reference cards are running at 65% fan speed and the non-reference are on auto.

[img]

Ok, I was imagining 38 reference 6970s at 90% fan speed or something.  Nice setup

[ZombieDeity]

I have a 1350W PSU running 3x6990 just fine.

what's the PSU efficiency and how many watts are you pulling from the wall?

It's an 80 Plus Gold rated supply (Enermax MaxRevo), so it should be pretty efficient.  I wish I could tell you how much I'm really pulling, but I haven't bought a Kill-A-Watt yet. 

[haploid23]

I have a 1350W PSU running 3x6990 just fine.

what's the PSU efficiency and how many watts are you pulling from the wall?

It's an 80 Plus Gold rated supply (Enermax MaxRevo), so it should be pretty efficient.  I wish I could tell you how much I'm really pulling, but I haven't bought a Kill-A-Watt yet. 

one of the highest priced PSU and GPUs, yet you haven't bought a $15 kill-a-watt yet 

[ZombieDeity]

I have a 1350W PSU running 3x6990 just fine.

what's the PSU efficiency and how many watts are you pulling from the wall?

It's an 80 Plus Gold rated supply (Enermax MaxRevo), so it should be pretty efficient.  I wish I could tell you how much I'm really pulling, but I haven't bought a Kill-A-Watt yet. 

one of the highest priced PSU and GPUs, yet you haven't bought a $15 kill-a-watt yet 

Lol...  I know, right!  I kinda want one, but it would just tell me the same thing my electric bill tells me every month:  "Your wife is going to kill you."

[mizike29]

Yeah that have a really good 1200 watt but only 2 1500 watt PSUs   The THermaltaka and Antex 1200s have done well, but the 15k is worry free.  That silverstone strider 1500 watt is a beast.

[DeathAndTaxes]

So im running 2X6990 on a 1200w psu

I saw a bitcoin miner review on the web that claims the 6990 can draw up to 600w's on full load?

http://www.hardocp.com/article/2011/07/13/bitcoin_mining_gpu_performance_comparison/4

Anyone have any comment on that?

They are saying a 6990 will draw 600W.  It is an ENTIRE SYSTEM including a pair of 6990 and other ultra high end overclocked components will draw 1200W total at the wall.

The system in the review is beyond foolish.  8GB of ram ultra-overclocked i7 CPU, massive hard drive, etc.  Even still it is 1200W @ the wall.  So at 85% efficiency (a guess) that is ~1000 DC watts (power supplies are always rated in DC wattage, AC wattage will be higher due to PS inefficiency).   How much of that 1K is due to the rest of system? Who knows.  The review is kinda useless.  If the system has 100% CPU bug and they didn't use affinity an overclocked i7 burning all cores @ 100% load can easily use 120W by itself.

If they wanted to do a real review they would record wattage of various cards on a usb linux key with no other components, measured at the wall, and they use power supply efficiency chart to figure actual DC load.  Take the system at idle (or single core @ 100% for 100% CPU bug) to figure actual draw of cards.

[mizike29]

Do not try to run two 6990s on a 850 watt PSU, it will fail, even a 1000k watt power supply it will cause issues for sure, unless you have a very low power rig in general for the rest of the rig.  Its not just the two cards, but I have seen the ones I have built blow the thermaltake 1000watt power supplyes a couple of times already, its just a lot of stress on the PSU if you run it for mining 24/7 with the rest of the system and the heat.  It can be done for sure, but your much better off having some room to play with.  Definitely do not go lower then a 1000 watt PSU for mining with those cards.

[DeathAndTaxes]

Do not try to run two 6990s on a 850 watt PSU, it will fail, even a 1000k watt power supply it will cause issues for sure, unless you have a very low power rig in general for the rest of the rig.  Its not just the two cards, but I have seen the ones I have built blow the thermaltake 1000watt power supplyes a couple of times already, its just a lot of stress on the PSU if you run it for mining 24/7 with the rest of the system and the heat.  It can be done for sure, but your much better off having some room to play with.  Definitely do not go lower then a 1000 watt PSU for mining with those cards.

Meh.

Two 6990 w/ underclocked memory plus low wattage mining system will draw <800W.  If it blows a 1000W PS then the PS is junk unable to even delivery 80% of rated load before failure.  That being said trying to put it on 850W supply is pushing it.


Of course a lot depends on the rest of build components.  A 45W seprom makes it easier than an i7 quad core.  I don't know why every miner doesn't have a kill-a-watt in order to better estimate their own loads.

[mizike29]

THats what im saying, if your pushing your two 6990s like you should and you have a good system overclocking it, running strong, you want a 1k wall thermaltake at minimum, anything less is just going to die, no reason to push it, now if you run just the cards, basic system you can get away with it, but if your trying to keep it running 24/7 for awhile, then the thermaltake 1000 watt is the best option for the price.  15k are overkill but pretty expensive.  RIGHT NOW THE  Corsair HX1050 is out replacing the 1000 watt and is always a good choice.