The real power consumption of your GPUs. Surprising results! What about the RTX 3070M?
Does the power consumption shown by your mining OS match what your rig actually draws from the wall? After our RTX 3070M review, a viewer suggested we check "at the plug" whether the card really used 90 watts. So in this video (in French), we measure the real consumption of three graphics cards with a wattmeter and compare it with the values shown in HiveOS. The results are surprising, especially for the RTX 3070M.
Video from 2022: the figures below date from that time, when Ethereum could still be mined with graphics cards. See "What about today?" at the end of the article.
The starting point: an RTX 3070M rated at 90 W
In our first review, the RTX 3070M, a mining card built around a laptop chip, reached 65.5 MH/s on Ethereum with a consumption estimated by HiveOS at 87 to 90 watts. Suppliers also advertised it at around 90 W, and this low power draw made it, on paper, one of the most efficient cards of the moment. That figure still had to be checked at the plug.
The method: a wattmeter and a subtraction
Some American YouTubers use a PMD, a device that measures a card's power draw directly. We didn't have one, so we chose a simple method, with a wattmeter plugged in between the wall socket and the rig.
- Measure the total consumption of the rig while it mines with the card being tested.
- Remove the card from the rig completely.
- Restart the rig, checking that the overclocking of the other cards has not changed, then restart the miner.
- Measure the total consumption without the card: the difference between the two readings is the card's real consumption.
Each measurement was repeated several times, removing and reinstalling the card. The values were the same every time to within 3 watts, and we kept the average. The cards were tested on Ethereum, then on Flux, to see whether the gap depends on the algorithm.
Results on Ethereum
- RTX 3070 (at 60 MH/s): 117 W shown in HiveOS, 137 W measured at the plug, i.e. 20 W more and a 14% gap.
- RTX 3070M: 88 W shown, 122 W measured, a 27% gap. This is where it hurts.
- GTX 1660 Super, a card known for its low power draw: 78 W shown, 90 W measured, i.e. 12 W more and a 13% gap.
All the cards draw more than HiveOS shows, then, but the gap on the RTX 3070M is much larger than on the other two.
Results on Flux
On Flux, you cannot lock the core clock as you do on Ethereum: you have to set the overclock and a power limit, here 140 W. HiveOS then shows 140 W of consumption for each card.
- RTX 3070: 159 W measured instead of 140 W, i.e. +12%.
- RTX 3070M: 152 W measured, i.e. +8%. With a power limit, no bad surprise: far from the 27% seen on Ethereum.
Why such a gap?
We put forward a hypothesis: the driver might not count the power going through the riser or the motherboard's PCIe slot (a BTC-S37 board here). Cards derived from laptops could be especially affected, since a laptop doesn't really have a PCIe slot. We contacted a supplier to report the gap: the supplier only advised us to try other overclocking settings, as if overclocking could explain the difference, and we got no other answer.
Is the RTX 3070M still worth it?
Yes, but less than expected. On Ethereum it draws 122 W versus 137 W for a standard RTX 3070: you save 15 W, whereas the values shown by HiveOS (88 W versus 117 W) suggested savings of almost 30 W. It remains one of the best cards in terms of efficiency: it draws a little less and runs cool, which confirms the strengths we noted in our first review.
Whether it is worth it against a standard card sold at the same price is another question: its warranty is somewhat more limited, which changes the calculation. It is up to you.
The lesson applies to every card: the consumption shown by the software is an estimate, and often an optimistic one. To calculate a rig's profitability, the measurement at the plug is what counts.
What about today?
Since Ethereum moved to proof of stake on 15 September 2022, Ethereum can no longer be mined with graphics cards and GPU mining income has collapsed: the hashrates above are now only useful for comparison. The method, however, still applies to any machine, ASICs included: a wattmeter between the wall socket and the miner gives you the consumption that really matters for your electricity bill.
To go further, read our RTX 3070M review. For a mining project today, browse our ASIC miners and estimate your earnings with our Bitcoin mining profitability calculator, entering the machine's real power consumption. A question before you buy? Contact us.