CPU Comparison

The Intel Xeon E3-1558L v5 and the Intel Processor U300 sit at opposite ends of Intel’s design philosophy, yet their average benchmark scores are nearly identical. The Xeon posts an average score of 1882, while the U300 scores 1881, a difference of just 0.1%. Both processors land in the 43rd percentile of all CPUs, meaning they occupy the same performance tier overall. However, this parity masks a stark split in how they achieve it. The Xeon is a 4-core, 8-thread server part from 2016 with a 45W TDP, while the U300 is a 5-core, 6-thread mobile chip from 2023 with a 15W TDP. The data shows two very different workloads: the older Xeon dominates in one multi-threaded test, while the newer U300 wins three of four head-to-head benchmarks, including a massive single-core advantage.

The Verdict

The benchmark results suggest a clear division of labor. The Intel Processor U300 is the better choice for single-threaded and lightly-threaded workloads, which is the domain of everyday computing. Its Cinebench R23 single-core score of 1616 crushes the Xeon’s 918, a 43.2% lead. In Cinebench R15 single-core, the U300 scores 222 versus the Xeon’s 92, an even more dramatic 58.6% gap. For users running office applications, web browsing, or any software that relies on high clock speeds, the U300 is the decisive winner. It also wins the Cinebench R15 multi-core test with 781 points against the Xeon’s 655, a 16.1% margin.

The Intel Xeon E3-1558L v5, however, is not obsolete. It wins the Cinebench R23 multi-core test with 6508 points versus the U300’s 4905, a commanding 32.7% lead. This suggests that under sustained, heavily-threaded loads, such as video rendering or scientific computing, the Xeon’s 8 threads provide a significant advantage. The Xeon also supports ECC memory, which the U300 does not, making it the only option for systems that require error-correcting memory. The U300 is active production and has a launch MSRP of $193, while the Xeon is end-of-life with a launch MSRP of $396. The verdict: pick the U300 for responsive, single-core-driven tasks and mobile efficiency; pick the Xeon for multi-threaded server-style workloads and ECC reliability.

Architecture Differences

The two CPUs are separated by seven years of architecture evolution. The Xeon E3-1558L v5 uses the Skylake-H architecture on a 14 nm process node, with a die size of 171 mm² and 2,300 million transistors. It has 4 cores and 8 threads, with 64 KB of L1 cache per core, 256 KB of L2 per core, and 8 MB of shared L3 cache. Its base clock is 1900 MHz with a boost clock of 3.30 GHz. The U300, by contrast, uses the Raptor Lake-U architecture on a 10 nm process node. It has 5 cores and 6 threads, a hybrid layout typical of modern Intel designs, with 80 KB of L1 per core, 1.25 MB of L2 per core, and the same 8 MB of shared L3. Its base clock is much lower at 1200 MHz, but its boost clock is significantly higher at 4.40 GHz.

The transistor count and die size for the U300 are not provided, but the architectural differences are clear. The Xeon’s Skylake-H is a monolithic server design from 2016, while the U300’s Raptor Lake-U is a newer, more power-efficient mobile design. The Xeon supports both DDR3 and DDR4 memory with a dual-channel bus and a memory bandwidth of 34.1 GB/s. The U300 supports DDR4 and DDR5, also dual-channel, but its memory bandwidth is not listed. The Xeon offers PCIe Gen 3 with 16 lanes, while the U300 offers PCIe Gen 4 with only 8 lanes. Integrated graphics differ as well: the Xeon has Iris Pro Graphics P555, while the U300 has UHD Graphics 48EU. The Xeon is a server/workstation part on the Intel BGA 1440 socket, while the U300 is a mobile part on the Intel BGA 1744 socket. The Xeon supports ECC memory; the U300 does not.

FAQ

Q: Which processor has the higher single-core performance?

A: The Intel Processor U300 wins decisively. In Cinebench R23 single-core, it scores 1616 versus the Xeon’s 918, a 43.2% advantage. In Cinebench R15 single-core, the U300 scores 222 versus 92, a 58.6% lead.

Q: Does the older Xeon beat the newer U300 in any benchmark?

A: Yes. The Xeon E3-1558L v5 wins the Cinebench R23 multi-core test with 6508 points against the U300’s 4905, a 32.7% margin. This is its only head-to-head win.

Q: What are the core and thread counts for each CPU?

A: The Xeon has 4 cores and 8 threads. The U300 has 5 cores and 6 threads. Despite having fewer threads, the U300 wins two of the three multi-core tests.

Q: Which processor supports ECC memory?

A: Only the Intel Xeon E3-1558L v5 supports ECC memory. The Intel Processor U300 does not, which makes the Xeon the only choice for systems requiring error correction.

Q: How do their average benchmark scores compare?

A: They are nearly identical. The Xeon has an average benchmark score of 1882, and the U300 has 1881. The delta is 0.1%, placing both in the 43rd percentile of all CPUs.

Q: What are the TDP differences between the two?

A: The Xeon has a TDP of 45W, while the U300 has a TDP of 15W. This makes the U300 significantly more power-efficient, which is expected given its mobile market segment.

Specification Differences

The two processors differ on nearly every specification except for the shared L3 cache size of 8 MB. The Xeon has 4 cores and 8 threads, while the U300 has 5 cores and 6 threads. The Xeon’s base clock is 1900 MHz, and its boost clock is 3.30 GHz. The U300’s base clock is 1200 MHz, and its boost clock is 4.40 GHz. TDP is a major difference: 45W for the Xeon versus 15W for the U300. The socket is different, Intel BGA 1440 for the Xeon, Intel BGA 1744 for the U300. The architecture is Skylake-H versus Raptor Lake-U, with process nodes of 14 nm and 10 nm, respectively.

The cache layout differs: the Xeon has 64 KB of L1 per core and 256 KB of L2 per core, while the U300 has 80 KB of L1 per core and 1.25 MB of L2 per core. Memory support diverges: the Xeon supports DDR3 and DDR4, while the U300 supports DDR4 and DDR5. The Xeon has a listed memory bandwidth of 34.1 GB/s, while the U300 has none listed. ECC memory is supported only on the Xeon. PCIe capabilities differ: the Xeon offers Gen 3 with 16 lanes, while the U300 offers Gen 4 with 8 lanes. Integrated graphics are Iris Pro Graphics P555 on the Xeon versus UHD Graphics 48EU on the U300. The market segments are Server/Workstation versus Mobile. The Xeon is end-of-life with a launch MSRP of $396, while the U300 is active with a launch MSRP of $193. The Xeon’s production status and release date (2016-05-30) are older than the U300’s (2023-01-03).

Head-to-Head Benchmarks

The head-to-head data reveals a clear pattern of the U300 winning on single-core and the Xeon winning on one specific multi-core test. In Cinebench R15 multi-core, the U300 scores 781 against the Xeon’s 655, a 16.1% win. This is surprising given the Xeon’s higher thread count, but the U300’s higher boost clock likely compensates. In Cinebench R15 single-core, the U300’s 222 points dwarf the Xeon’s 92, a 58.6% margin. This is the largest difference in any test, highlighting the Xeon’s age in single-threaded performance.

The Cinebench R23 results flip the script. In multi-core, the Xeon scores 6508, beating the U300’s 4905 by 32.7%. This is the Xeon’s only win, and it is substantial. The newer U300, despite having more cores, falls behind in this sustained multi-threaded workload. In Cinebench R23 single-core, the U300 wins again with 1616 points against the Xeon’s 918, a 43.2% lead. The U300 wins three of four benchmarks, but the Xeon’s single win is the largest margin of victory. The average benchmark scores are 1882 for the Xeon and 1881 for the U300, confirming their overall parity. The nearest rivals for the Xeon include the Intel Xeon E3-1270L v4 with a delta of -0.1% and the Intel Xeon D-1531 with a delta of -0.1%. The U300’s nearest rivals are the same chips, with the Xeon E3-1558L v5 at a delta of 0%.

Where Each One Wins

The Intel Processor U300 wins in scenarios that demand high clock speeds and responsive single-threaded performance. Its Cinebench R23 single-core score of 1616 is 43.2% higher than the Xeon’s, making it the clear choice for applications like office productivity, web browsing, and light content creation that rely on single-core speed. The U300 also wins the Cinebench R15 multi-core test, suggesting it handles moderately threaded workloads well despite its lower thread count. Its 15W TDP makes it suitable for thin-and-light mobile devices, and its active production status means it is readily available. The U300’s PCIe Gen 4 support is a modern advantage, though it has fewer lanes than the Xeon.

The Intel Xeon E3-1558L v5 wins in sustained, heavily-threaded workloads. Its Cinebench R23 multi-core score of 6508 is 32.7% ahead of the U300, indicating superior performance in tasks like video rendering, 3D modeling, and multi-threaded server applications. The Xeon’s support for ECC memory is a critical feature for workstations and servers where data integrity is paramount. Its 16 PCIe Gen 3 lanes offer more expansion capability than the U300’s 8 Gen 4 lanes, which can matter for add-in cards. The Xeon’s server/workstation market segment and 45W TDP suggest it is designed for always-on, heavily-loaded systems, not battery-powered devices. While it is end-of-life, its performance in the R23 multi-core test proves it still has relevance for specific multi-threaded use cases. The data suggests a trade-off: the U300 for speed and efficiency, the Xeon for raw multi-threaded power and ECC reliability.