First Tests! Intel's 13th Gen Core U Series, 'Raptor Lake' CPU Power for Thin Laptops

Intel's 13th Generation "Raptor Lake" processors kicked off months ago on desktops with the Intel Core i9-13900K flagship CPU on down, then progressed to laptops with the introduction of the most powerful Core i9 laptop CPUs earlier this year, in the 13th Gen Core H Series. But, as anyone shopping for an ultraportable laptop could tell you, the low-voltage processors needed to power the thinnest and lightest laptops hadn't yet caught up. Even the most recent models were built around 12th Gen chips.

That all changes with the first 13th Gen U Series chip in our labs and already tested, arriving in the soon-to-be-reviewed Asus Zenbook S 13 OLED (UX5304). While our full review is still in the works, our initial tests give us a telling look at what the newest U Series chips bring to the market, and whether you should be excited to upgrade to one of the first ultraportable laptops to get them.

An Introduction to Intel's U Series

Intel's U Series processors aren't made for heavy gaming or crunching massive numbers like a workstation PC. Instead, the U Series is built to give you peppy performance in lower-cost mainstream systems and thin-and-light ultraportables, especially in the latter designs, where little or no room may be available for bulky cooling fans. Meanwhile, battery life is expected to stretch well beyond the 10 hours or so that would qualify as "all-day" battery life.

Made to run on just 15 watts of power, this is really where the rubber meets the road on Intel's biggest claims about efficient performance. Will the new chips deliver better test results than last year's best U Series systems? It's easy to think that such gains are pretty much guaranteed. (Results vary from laptop design to laptop design with the same chip inside, of course.) But that low voltage and tight thermal envelope mean that U Series CPUs are already optimized for efficient performance. We'll have to look at the test results to see if any gains have been made.

At last, we have the first 13th Gen U Series CPU in our lab, in a review unit of the Asus Zenbook S 13 OLED (UX5304). Before we finish full benchmarking of that machine for our review, we wanted to take a closer look at the Intel Core i7-1355U processor it has inside. Our review unit is outfitted with that 10-core/12-thread (two Performance cores; eight Efficient cores) CPU, augmented by 32GB of LPDDR5 memory, and relying on the Intel Iris Xe Graphics that are part of the chip.

Testing Intel Raptor Lake U Series: No First-Test Fireworks

We'll be following up with a full review of the Asus Zenbook S 13 OLED (UX5304) in the coming days, but for this piece, our focus is far more granular: We want to see how well the new Intel Core i7-1355U fared when compared with the previous 12th Gen version—in this case, the Intel Core i7-1255U. As the "Alder Lake" equivalent of the Raptor Lake model we've just tested, it's the closest comparison to make. (It's a 10-core chip just like the 1355U, with two P-cores and eight E-cores.) The 1355U is the second-highest chip in the new U Series line, with an Intel-listed Core i7-1365U touting the same core/thread breakout but slightly higher clocks.

Of course, we also compared this chip with Apple's latest ultraportable-class CPU, the Apple M2 processor found in the Apple MacBook Air. While Apple doesn't explicitly label this CPU as being made for ultraportables, its use in the MacBook Air (and its other lower-power uses compared with Apple's latest M2 Max and M2 Pro processors) make it the clear equivalent among current Apple Silicon options.

Finally, we also looked at the numbers for the AMD Ryzen 7 Pro 6850U, the chip found in last year's Editors' Choice-award-winning Lenovo ThinkPad Z13. Again, comparing products from different manufacturers in different chassis is a game of apples and oranges, as different chip makers have differing design philosophies and manufacturing processes, and thermals differ from laptop design to laptop design. But the 6850U is clearly a capable ultraportable chip from Intel's most direct mobile-CPU rival, and thus worth comparing.

Productivity and Content Creation

Firing up our usual suite of performance tests, we benchmarked the Intel Core i7-1355U using tests that will be familiar to any reader of our reviews, starting with PCMark10, which runs through a simulated batch of work tasks that includes word processing, spreadsheet manipulation, web browsing, and videoconferencing to measure real-world productivity.

Our next three benchmark tests focus on processor-intensive workloads. Starting with multi-threaded tests, Maxon's Cinebench R23 uses that company's Cinema 4D engine to render a complex scene, while Geekbench 5.4 Pro by Primate Labs simulates popular apps ranging from PDF rendering and speech recognition to machine learning. (Higher scores are better.) We also use the open-source video transcoder HandBrake 1.4 to convert a 12-minute video clip from 4K to 1080p resolution (lower times are better).

While we usually include the PugetBench for Photoshop test from Puget Systems to rate a PC's performance for content creation and multimedia applications, we ran into multiple errors when we tried to run the older Photoshop 22 on the new hardware and had to drop it from this comparison.

In PCMark10, the 13th Gen-powered Asus Zenbook 13 posted scores toward the front of the pack, edging ahead of top-rated systems by sometimes several hundred points. However, it didn't take the top spot, falling behind both the Intel Core i7-1255U-based Lenovo Yoga 7i 14, as well as the AMD-powered Lenovo ThinkPad Z13.

On HandBrake and Cinebench, the Core i7-1355U was less impressive, falling below the middle of the pack, despite its newer processor. It took more than 10 minutes to convert a video clip in HandBrake—nearly twice as long as the leading Dell Inspiron 14 2-in-1 (5:44)—with most competitors falling in the seven- or eight-minute range.

In Cinebench rendering tests, it fell even farther back, placing behind several older systems. Interestingly enough, however, the Raptor Lake Core i7-1355U was within only 11 points of the Apple MacBook Air, which uses the Apple M2 processor.

Finally, with Geekbench, the same general spread is evident, with the 13th Gen CPU falling short of several competitor scores. It's still well within a decent range for day-to-day performance, but for a generational update to Intel's hardware, we expected to see clearer victories in these essential processing tasks.

Graphics Tests

While ultraportable laptops aren't built for the gaming or rendering tasks that you'd want a gaming laptop or workstation for, you'll still find plenty of graphics-performance aspects to daily work that any laptop should be able to handle. Whether it's plotting charts, editing photos, or streaming media, you still need some measure of graphics capability. The integrated Intel Iris Xe graphics that come with the Core i7 CPU are perfect for this sort of work, and we test this performance alongside other processor functions.

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We test integrated graphics with a pair of DirectX 12 tests from UL's 3DMark: the basic Night Raid, and the more demanding Time Spy. Higher scores indicate better performance. Beyond that, we run two cross-platform tests in GFXBench 5, which focus on both low-level routines like texturing and high-level, game-like image rendering. The 1440p Aztec Ruins and 1080p Car Chase tests, rendered offscreen to accommodate different display resolutions, exercise graphics and compute shaders using the OpenGL programming interface and hardware tessellation respectively. The more frames per second (fps), the better.

Again, the 13th Gen Core i7 produced acceptable (but not leading) performance. In both 3DMark tests, the Raptor Lake CPU delivered one of the lower scores in our batch of comparisons. The 13th Gen U Series came in ahead of the Dell Inspiron 14 2-in-1 and the Lenovo ThinkBook 14s Yoga Gen 2, but fell behind everything else, whether Intel-based laptops or the AMD-powered Lenovo ThinkPad Z13.

The gaps are much closer in the GFXBench 5 Aztec Ruins test, where the 13th Gen Zenbook was within a couple of frames of the Microsoft Surface Pro 9 and the HP Spectre x360 13.5, but well ahead of the Dell Inspiron 14 2-in-1 and the Lenovo ThinkBook 14s. In the Car Chase subtest, the 13th Gen CPU pushed even farther ahead, falling more solidly in the middle of the group.

Verdict: Early Days, More Data Necessary

When it comes to comparing the new Intel Core i7-1355U with the older 12th Gen Intel Core i7-1255U, the uncomfortable reality in our Zenbook S 13 sample is that we see no significant performance gains delivered by the new processor. While it's efficient with its 15W power, and capable in both day-to-day tasks and basic graphics demands, it's not markedly better on raw performance. In most respects, this CPU's performance is the same or slightly lower.

Plus, when compared with the AMD Ryzen 7 Pro 6850U and the Apple M2, this 13th Gen Intel processor comes up lacking, as it presents in this Zenbook. These competitor chips are faster and more powerful than the Raptor Lake processor in the Zenbook S 13—often by a large margin. Although again, we emphasize: This is one implementation, in one laptop. Still, so far, we're left disappointed with performance that's just a smidge more, in places, than what we already had last year.

In short: The jury's still out. We didn't see a clear lead over last year's U Series 12th Gen processors in this first sample, so we'll want to see what else comes down the 13th Gen laptop pike before making any judgments. What we saw from the Zenbook 13 is not bad, sitting comfortably alongside some of the best ultraportables we've seen this year and last. But if you were expecting considerable year-over-year improvements, you'll have to wait and see if matters improve on the second wave of 13th Gen U Series laptops soon to come.

Again, we must repeat: This may be a singular case, and performance could be impaired in the Asus Zenbook S 13 OLED for any number of reasons, ranging from thermal management to component choice to other Asus design particulars. Or it could simply be an issue with poorly optimized software. For a first impression, we're left underwhelmed, but we're poised and hopeful for 13th Gen's next at-bat in PC Labs.