Topic: 650W Enough for 2x 1080 Ti ?? (Read 376 times)

Thanks for the reply QuintLeo.

I didn't mean $1-2/day total. I meant $1-2/day difference in 100% power and 70% power. But honestly I can't really tell because Nicehash is always changing the projected profit. I get $14-$16/day depending on power settings with 2x 1080 Ti.

I've got
2x 1080 Ti SC2 (EVGA) ~$15/day
2x 1070 Ti Mini (ZOTAC) ~$10/day
1x 1070 SC (EVGA) ~$5/day

on 3 different machines :/ need bigger power supply. I'm not even looking for 650W anymore. Waiting for 1000-1300W.

and I average .0019-.0022BTC/day or $27-32/day of course depending on price of BTC.

Is that about expected?

*and yes I've been running all cards at anywhere between 70% and 85% power limit. So clock speeds do drop.

 Seasonic Prime power supplies are a single-rail design, there is no issue with "split rails" like on the CHEAP power supply you are talking about.

 For that matter, every power supply that Seasonic has made and sold under it's own name for YEARS have been of the "big single +12V rail, then convert the OTHER voltages FROM that big +12V rail" design.

 EVGA SC 1080 ti cards should be making quite a bit more than $1-2 a day net after electric right now via Nicehash - a quick check on whattomine shows Nicehash best algorithm listed on a single 1080 ti having a NET PROFIT (at my very low electric cost) of about $8/day if running it for high hashrate.


 To MrNice9uy:

 OF COURSE your core clock speeds drop when you lower the TDP - boost clock is limited by several factors, the biggest one of them is the power available to run the card and GPU on.
 It also drops temps, as the card doesn't have as much power to dissipate, IF the fans are set at a "fixed" speed - will still drop even on a "fan curve" but not as much since the fans will slow down some.



 The reasons a lot of us set the TDP lower are multiple:

 1) Better efficiency, so we can run MORE cards on the same amount of power and end up generating more coin per watt.
     Mostly applies to folks that are at or close to their power limit for their mining area, or to folks with VERY VERY HIGH electric rates.
     1080 ti in specific, 250 watt TDP MIGHT genrerate as high as 780 sol/s on a very good cooling card like an Aorus, but at 150 watt TDP the same card still generates around 620 - drop the power 40% only lose 20% income.
     Cards with lesser cooling will lose less hashrate, as they will still probably manage the 620 "low power" hashrate but WON'T manage the 780 at high power.

 2) Lower temperatures, for better lifetime of the card and the fans on it.

 3) Some folks mine in areas it gets HOT AND HUMID in the summer, at which point they HAVE to drop the TDP to get the card to stay cool enough to run at all or to avoid temp-limit throttling.
     It's a bad idea to assume standard "mechanical" Air Conditioning as that stuff adds 30-40% to your ELECTRIC USAGE to keep your rigs cool.


 In my case, it's also due to infrastructure limitations - the place I'm in has a lot of standard 117 VAC 15 amp "duplex" outlets, but I'm not allowed to "rewire" the place, so building rigs that can run at 6 amps draw using 5 1070 ti cards set for EFFICIENT mining allows me to make the best usage of the available power without pushing the wiring past the 80% derate for 24/7 operation that the NEC requires for SAFETY reasons.

Yes, I thought so.

PCI-E risers power draw is negligible.

I was just going to explain it to you that the power consumption is more than the coin you get in return.

But I just tried it out and from just looking at Nicehash it seems I'd lose $1-2/day in coin and only save $0.50/day in electricity cost.

My core clock speeds drop from 1900MHz to 1600MHz when I lower power limit.

2x EVGA GTX 1080 Ti SC2


Anyone else care to share their experience on this?

*I suppose temps would be considerably higher at 100% power. 81C vs 71C.

why did some people set limit load at 70%? why not let it 100% so you can get much more coin?

no sane person mines with a 1080-TI at 100% power, unless they're also trying to cook bacon on their mining rig.

You kinda lost me with the 12V 100W and 12V 350W.

Here's what the 650W PSU that I was looking at says on the label

+3.3 V:
Maximum Power: 20 A, 100 W

+5 V:
Maximum Power: 20 A, 100 W

+12 V:
Maximum Power: 52 A, 648 W

-12 V:
Maximum Power: 0.3 A, 3.6 W

+5 VSB:
Maximum Power: 3 A, 15 W

Now, can you explain what is what again? Or at least as much as you know? I know the +12V goes to main components; and I'm not sure about the rest but I would assume the +5V and +3.3V go to things like molex and sata. But I don't know exactly which is which.

It's not always like this.
Take a look at the PSU's Label, the 12v rail (yellow) was indicated with 2 wattage.
The 1st one would be for the 4Pin Molex, sata, processor and MotherBoard 12volts.
The Second was for the 6Pin or 8Pin Connectors.
Although, cheap and substandard power supplies does not have this kind of feature.
Getting the total power consumption of all the component wasn't the correct formula.

My Gaming Rig PSU for example, the label said 12v max 100W and another 12v max 350W.
The 350W was allotted only for the GPU's supplementary Power. This is where you will base on how many cards you can power.
A different scenario when you're using a 4pin Molex to 8/6-pin Adapter. It will get its power from the other rail.

 PCI-E risers can use 80+ watts - but most of that is feeding the GPU via the PCI-E bus power connections, it's NOT "in addition" to the actual GPU power.
 The riser ITSELF might use as much as 20 watts but more likely 5-10 in the "voltage conversion" circuitry when running at full load.

I'd recommend a 1200W Titanium PSU fed by 240W 30A circuit to achieve maximum efficiency @ 50% load.

1080 ti has a TDP of 250 W, The mathematical calculation is 2x250 = 500 W. if 650 W PSU only has the remaining 150 W, I think it's too less. not to mention POWER for MOtherboard, SSD, and USB RISER and other devices. It's safer to use a PSU 700 or 850 W, this is to keep the other device from less power.

PCI risers use that much power? 

Noticed that all have at least 1600w PSU even if they use only 50% of the available power at runtime.
Always better have flexibility

Agreed, better have some xtra power... keeping in mind that you can easy limit power consumption using nvidia tools (before starting the miner). For example my 6 x 1070 rigs can mine with 98% efficiency on equihash / ethash / neoscript using only 850 W (66% power limit) for all the setup. Same on CryptoNight , 96% efficiency with only 700w (75w per 1070 instead of 150).
Try to play with overclocking + power limit, this is the key

It has to be enough but better to take a bit more powerful power supply. Better to have at least 10% of the load in stock

With a 12 Year Warranty it's hard to complain about the fan. We will see.

I'm not sure what kind of system you are using but with only 2 GPU no risers and no way RAM, SSD, & motherboard = 100W. CPU is G3900 and = 18W max, 10W average at 100% mining ETN. Only time 220W is needed per GPU is to POST. Other than that, as previously stated, they only need 185W.

1 x gpu, around 220w
1 x gpu, around 220w
1 x PCI riser 30w
1 x PCI riser 30w
1 x CPU 35w - 65w
RAM, SSD, motherboard - 100w

Total around 665w. Because you should not run your PSU for more than 80% load 24/7, add 20%, which comes to 798, so 800w PSU as minimum.

Running the cards at 185, it should have enough capacity.

I'd be more worried about the junk "fancy name sleeve bearing" fan the Prime line uses.

Have been running 2x zotac 1080ti FE for weeks on 650w evga g2 with no issues. cards set to 70% tdp in msi afterburner