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We measure real-world power consumption using Powenetics testing hardware and software. We capture in-line GPU power consumption by collecting data while looping Metro Exodus (the original, not the enhanced version) and while running the FurMark stress test. We also check noise levels using an SPL meter. Our test PC remains the same old Core i9-9900K as we've used previously, to keep results consistent.
We also test on our newer 13900K PC using PCAT v2 hardware in all of our gaming benchmarks, which gives a wider view of power use and efficiency. We'll start with the gallery of our PCAT results — note that FPS/$ uses the official MSRPs for the RX 7000- and RTX 40-series cards, while FPS/W (ie, efficiency) uses the measured power consumption.
We have results for our 1440p and 4K testing, along with the manually overclocked 4K testing, except on the RTX 4080. That was originally reviewed on our previous i9-12900K test PC, and while we retested standard performance on the 13900K system, we didn't retest with overclocking, so those lines are blank (but we left them in place so the images are all the same dimensions).
There's a lot to parse in the above tables, but if we just focus on the Sapphire card for the time being, what you'll see is that performance per watt and performance per dollar both drop compared to the reference card. That's no surprise, since the Sapphire card consumes more power, costs more, and offers a barely measurable change in performance in most of our testing.
Looking at the bigger picture, the RTX 4080 delivers the best efficiency out of the cards we've tested so far, while the RTX 4070 Ti offers the best "value" in terms of FPS per dollar. That's not to say it's a great value, or that other cards like the RX 6650 XT wouldn't beat it (we haven't retested that on the new PC yet), but of the latest generation GPUs, the RTX 4070 Ti delivers slightly more FPS per dollar spent — and it would have done much better if it had inherited the RTX 3070 Ti price!
Of course, that's predicated on any of the cards being available at MSRP. Newegg does list a couple of RTX 4070 Ti cards at $799.99, in stock, and the same goes for the RX 7900 XT, with the XFX reference model actually priced $20 below MSRP right now. The RTX 4080 starts at $1,269.99 (there's a PNY model that's also backordered at MSRP). The RX 7900 XTX meanwhile starts over $400 above MSRP, making it far and away the worst value at present.
Our previous power testing results are still valid, though they're limited to two scenarios: FurMark and Metro Exodus. Both test scenarios last about 10 minutes, though Metro does have a "break" between loops that allows the GPU to recover slightly.
Sapphire's RX 7900 XTX Nitro+ ends up eclipsing everything except for the RTX 4090 and RTX 3090 Ti when it comes to power use, and it's not that far behind those in our gaming test. Power draw averaged 425W in Metro, just 6W less than the 3090 Ti and 10W less than the 4090, and also 73W more than the reference 7900 XTX and 128W more than the RTX 4080. So much for those efficiency gains AMD was talking about with RDNA 3 — they clearly don't apply when you redline the GPU.
You can of course opt to save power by switching out of the default performance mode, which might not be a bad idea. Manual overclocking, as we showed above, would only make things worse.
The clock speeds help to explain the higher power draw, as, in FurMark, Sapphire's card averaged just over 2 GHz, compared to 1.66 GHz on the reference model. While gaming, it also averaged 2.8 GHz compared to 2.56 GHz on the reference card.
We don't usually dig too much into the voltages, but it's worth mentioning that in our Metro testing, the reference card had an average VDDC of 0.895V while under load, compared to the Sapphire card's 0.988V for the same test sequence. That extra 0.93V makes a rather large difference in power use when combined with the higher clock speeds.
The good news is that temperatures are basically the same on the Sapphire card and on the reference XTX, despite the higher power draw. Both top out in the 65C range, with the reference XTX running its fans at up to ~1650 RPM compared to just 1450 RPM for the Sapphire card. That impacts the noise level as well.
We check noise levels using an SPL (sound pressure level) meter placed 10cm from the card, with the mic aimed right at the center fan. This helps minimize the impact of other noise sources like the fans on the CPU cooler. The noise floor of our test environment and equipment is around 32 dB(A).
After running Metro for over 15 minutes, the Sapphire RX 7900 XTX settled in at a fan speed of 38% and a noise level of 42.2 dB(A). That's only slightly higher than some of the quietest cards we've tested, which land at around 39 dB(A). The reference card meanwhile measured 49.9 dB(A), which is clearly audible over the ambient room noise. We also tested with a static fan speed of 75%, where the Sapphire generated 56.6 dB(A) of noise, so there's plenty of room for additional airflow and cooling if the fans need to ramp up — not that you'd normally want that.
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