Basically the Ryzen 9 4900HS operates with a 3.0 GHz base clock and 4.3 GHz boost clock, while the Ryzen 7 4800U can only muster 1.8 GHz base clock and 4.2 GHz boost clock.
Taken from Tom’s Hardware … Earlier this month, AMD announced the Ryzen 7 4800U and Ryzen 9 4900HS as the upcoming flagship mobile processors for the Ryzen 4000 U-and H-series, respectively. Although AMD’s tailoring the two chips to different markets, hardware leaker @_rogame has given us an alleged sneak peek at the potential performance difference between the two chips.
The Ryzen 7 4800U and Ryzen 9 4900HS (codename Renoir) share similar ingredients. Both APUs leverage AMD’s Zen 2 microarchitecture and are product of TSMC’s 7nm FinFET manufacturing process. Each processor has eight cores, 16 threads and 8MB of L3 cache. They even feature the same integrated graphics (iGPU), which consists of eight Vega graphics cores that peak at 1,750 MHz. But that’s where the similarities end.
The Ryzen 7 4800U is aimed at thin-and-light laptops, so it’s forced to run with a 1.8 GHz base clock and 4.2 GHz boost clock to respect the 15W TDP (thermal design power) limit. The Ryzen 9 4900HS, part of AMD’s HS design standard for the best gaming laptops, has a higher TDP. With a more generous 35W envelope, the Ryzen 9 4900HS operates with a 3.0 GHz base clock and 4.3 GHz boost clock.
According to the leaker, the Ryzen 7 4800U system was using LPDDR4x memory clocked at 4,266 MHz. This configuration enabled the Ryzen 7 4800U to achieve Physics and Graphics scores of 16,171 point and 3,543 points, respectively.
The Ryzen 9 4900HS reportedly put up a Physics score of 21,289 points and a Graphics score of 4,085 points in the same benchmark. Therefore, the Ryzen 9 4900HS appears to deliver up to 31.6% better performance, at least on the Fire Strike benchmark.
Read more at Tom’s Hardware