Intel Core i7-5775C vs Intel Core i7-8559U Comparison

The Intel Core i7-8559U and Intel Core i7-5775C are both 4-core, 8-thread processors that land in the same performance tier, with nearly identical average benchmark scores of 2225 and 2224 respectively. Despite this statistical tie, the two chips take fundamentally different paths to get there, and the head-to-head data reveals a fascinating split between Cinebench and Geekbench workloads that tells you more about their architectures than any single score could.

Head-to-Head Benchmarks

The i7-8559U dominates the Cinebench suite with consistent, narrow victories across every version of the test. In Cinebench R15 multi-core, it scores 703 against the 5775C's 660, a 6.5% advantage. That lead holds almost exactly in single-core R15 (99 vs 93, also 6.5%). Moving to R20, the margins tighten slightly in percentage terms but stay in the same range: 2933 vs 2750 for a 6.7% multi-core win, and 414 vs 388 for a 6.7% single-core win. The R23 results continue the pattern, with the 8559U posting 6984 vs 6549 multi-core (6.6%) and 986 vs 924 single-core (6.7%). Across all six Cinebench tests, the 8559U wins by a remarkably consistent 6.5% to 6.7% margin, suggesting a uniform clock-speed advantage that scales across both single-threaded and multi-threaded rendering workloads.

The story flips completely in Geekbench. The 5775C wins multi-core with 4989 vs 4293, a decisive 14% advantage. Its single-core lead is smaller but still clear: 1441 vs 1384, a 4% margin. This is a dramatic reversal — the same two chips that are nearly inseparable in Cinebench are separated by double-digit percentages in Geekbench multi-core. The Geekbench results are particularly striking because they invert the expected relationship: the 8559U has a higher boost clock (4.50 GHz vs 3.70 GHz) and wins every Cinebench test, yet loses Geekbench by a wide margin.

The overall win count favors the 8559U at 6 wins versus 2 for the 5775C. However, the magnitude of the 5775C's Geekbench multi-core victory (−14% delta) is more than double the 8559U's largest Cinebench win (6.7%). This is a case where the scoreboard doesn't tell the whole story — the 5775C's losses are narrow and consistent, while its wins are substantial.

Where Each One Wins

The i7-8559U is the clear choice for Cinebench-style rendering workloads. Its 6.5% to 6.7% edge across R15, R20, and R23 — in both single and multi-core — indicates that it will consistently finish rendering tasks noticeably faster. The consistency of the margin is notable; it suggests the 8559U's higher boost clock translates directly into rendering performance without any thermal or power throttling penalties that might be expected from a 28W mobile part.

The i7-5775C takes the crown in Geekbench, particularly in multi-core where its 14% lead is the single largest performance gap between these two chips in any test. This suggests the 5775C handles Geekbench's mixed workload — which includes memory-bandwidth-sensitive tasks and integer operations — more efficiently. The 5775C also wins Geekbench single-core by 4%, which is intriguing because the 8559U wins Cinebench single-core by 6.5%. These are not just different benchmark suites; they are measuring different aspects of CPU performance that favor each chip differently.

If your workflow is rendering in Cinema 4D or similar applications, the 8559U is the stronger performer. If your work involves the kinds of tasks Geekbench models — a mix of compression, encryption, image processing, and physics — the 5775C's 14% multi-core advantage makes it the better choice. For general productivity that doesn't stress the CPU heavily, the two chips are effectively interchangeable given their near-identical average scores.

Architecture Differences

The two processors come from different Intel families and target different market segments. The i7-8559U is a Kaby Lake-R mobile chip on the Intel BGA 1356 socket, built for laptops and ultrabooks with a 28W TDP. The i7-5775C is a Broadwell desktop chip on Intel Socket 1150 with a 65W TDP — more than double the power envelope. Both use Intel's 14 nm process node, but the die sizes differ significantly: the 8559U measures 123 mm² while the 5775C is considerably larger at 182 mm².

The cache configurations also differ. The 8559U has 8 MB of shared L3 cache, while the 5775C has 6 MB. Both share the same per-core L1 (64 KB) and L2 (256 KB) caches. Memory support diverges: the 8559U uses DDR4, while the 5775C uses DDR3 with a dual-channel bus and 25.6 GB/s of memory bandwidth. The 5775C also supports PCIe Gen 3 with 16 lanes from the CPU, while the 8559U's PCIe configuration is not specified.

The integrated graphics differ as well — the 8559U has Iris Pro Plus, while the 5775C has Iris Pro Graphics 6200. The 5775C is an unlocked multiplier part (part number SR2AG), while the 8559U is locked. The 5775C launched on 2015-05-14 with a launch MSRP of $366; the 8559U released on 2018-04-04 with no MSRP listed. Neither chip supports ECC memory, and both are listed as Active in production status.

Clock speeds tell a key part of the story: the 8559U has a 2.70 GHz base and 4.50 GHz boost, while the 5775C has a 3.30 GHz base and 3.70 GHz boost. The 8559U's much higher boost clock (0.80 GHz more) explains its Cinebench wins, while the 5775C's higher base clock (0.60 GHz more) and larger power budget may contribute to its Geekbench performance.

FAQ

Q: Which processor has a higher boost clock?

A: The Intel Core i7-8559U boosts to 4.50 GHz, which is 0.80 GHz higher than the i7-5775C's 3.70 GHz boost clock.

Q: How much faster is the i7-8559U in Cinebench R23 multi-core?

A: The i7-8559U scores 6984 compared to the 5775C's 6549, a 6.6% advantage.

Q: Why does the i7-5775C win Geekbench multi-core by such a large margin?

A: The 5775C scores 4989 versus 4293 for the 8559U, a 14% difference. This is the largest performance gap between the two chips in any benchmark, and it suggests the 5775C's architecture handles Geekbench's mixed workload more efficiently despite its lower boost clock.

Q: Do both processors have the same number of cores and threads?

A: Yes, both have 4 cores and 8 threads. They also share the same per-core L1 and L2 cache sizes at 64 KB and 256 KB respectively.

Q: What memory types do these CPUs support?

A: The i7-8559U supports DDR4 memory, while the i7-5775C supports DDR3 with a dual-channel bus and 25.6 GB/s bandwidth.

Q: Which processor is unlocked for overclocking?

A: The i7-5775C has an unlocked multiplier, while the i7-8559U does not.

The Verdict

The data paints a clear picture of two chips that achieve similar overall performance through completely different means. The i7-8559U is the better rendering processor, winning all six Cinebench tests by margins between 6.5% and 6.7%. Its 4.50 GHz boost clock gives it a consistent edge in both single-threaded and multi-threaded rendering workloads, and it does this while consuming just 28W — a remarkable efficiency advantage over the 5775C's 65W TDP.

However, the i7-5775C is the better Geekbench performer by a wide margin. Its 14% multi-core lead is the most significant performance difference between these two CPUs in any test, and it also wins single-core Geekbench by 4%. For workloads that resemble Geekbench's mix — which includes memory-sensitive and integer-heavy tasks — the 5775C is the stronger choice despite its older architecture and lower boost clock.

The average benchmark scores are nearly identical at 2225 for the 8559U and 2224 for the 5775C, and both sit at the 47th percentile of all CPUs. If you need a mobile chip for rendering work, the 8559U is the obvious pick. If you're building a desktop and your software behaves more like Geekbench than Cinebench, the 5775C's 14% multi-core advantage is too large to ignore. For general use, the two are effectively tied, and the decision should come down to platform considerations — mobile BGA 1356 versus desktop Socket 1150 — rather than raw performance.

Specification Differences

| Specification | Intel Core i7-8559U | Intel Core i7-5775C |

|---|---|---|

| Base Clock | 2.70 GHz | 3.30 GHz |

| Boost Clock | 4.50 GHz | 3.70 GHz |

| TDP | 28W | 65W |

| Socket | Intel BGA 1356 | Intel Socket 1150 |

| Architecture | Kaby Lake | Broadwell |

| Process Node | 14 nm | 14 nm |

| Die Size | 123 mm² | 182 mm² |

| L3 Cache | 8 MB (shared) | 6 MB (shared) |

| Memory Support | DDR4 | DDR3 |

| Memory Bus | Not specified | Dual-channel |

| Memory Bandwidth | Not specified | 25.6 GB/s |

| Integrated Graphics | Iris Pro Plus | Iris Pro Graphics 6200 |

| Market Segment | Mobile | Desktop |

| Release Date | 2018-04-04 | 2015-05-14 |

| Launch MSRP | Not specified | $366 |

| Multiplier Unlocked | No | Yes |

| Part Number | Not specified | SR2AG |