AMD announced its Ryzen 4000 U-series chips for laptops in January, but the lineup doesn't include any Ryzen 9 models. However, a Ryzen 9 4900U was spotted on UserBenchmark by hardware leaker @TUM_APISAK, pointing to a future CPU for thin-and-light laptops.

The chip should be based on the Zen 2 microarchitecture and take advantage of TSMC's 7nm FinFET manufacturing process. Like any other U-series part, the Ryzen 9 4900U is shown rated with a 15W, but it also features a cTDP (configurable thermal design power) between 10W and 25W.

This Ryzen 9 4900U in question shares the same configuration as the already announced Ryzen 7 4800U. You can expect the upcoming flagship to arrive with eight cores, 16 threads and 12MB of total cache. At the end of the day, the higher clock speeds on the Ryzen 9 4900U will ultimately set it apart from the Ryzen 7 4800U.

The scores from the UserBenchmark submission suggest that the leaked Ryzen 9 4900U is very likely an engineering sample. The Ryzen 7 4800U outscores the unreleased chip's numbers by a fairly substantial margin. Only the Ryzen 9 4900U's single-core result is closer to expectations.

Engineering samples aren't true indicators for final specifications. Furthermore, software typically has a hard time reporting unreleased hardware correctly. For what it's worth, UserBenchmark detected the Ryzen 9 4900U with a 1.8 GHz base clock and 2.35 GHz average boost clock; however, the Ryzen 7 4800U has a 4.2 GHz boost clock, so the Ryzen 9 4900U is expected to come with an even higher boost clock, such as 4.3 GHz or more. 

The UserBenchmark entry doesn't give any hints on the Ryzen 9 4900U's integrated graphics solution, but there shouldn't be any surprises here. The Ryzen 7 4800U is equipped with eight Vega cores ticking up to 1,750 MHz. The setup will probably transfer over to the Ryzen 9 4900U, unless AMD decides to beef up the clock speed a little.

In Intel's camp, there's the Intel Core i7-10710U hexa-core Comet Lake-U part and i7-1065G7 quad-core Ice Lake chip, which are the respective flagships of their lineups. On paper, the Ryzen 9 4900U has the advantage over the two Intel chips, based on core count alone. However, we won't understand the octa-core chip's real performance until AMD confirms it and it starts showing up in laptops -- which, considering the appearance of these benchmark results, shouldn't be far off.