Intel Core i5-5575R vs Intel Core i7-8665U Comparison

The Intel Core i7-8665U and Intel Core i5-5575R represent two distinct design philosophies from Intel, separated by three years of silicon evolution. The i7-8665U is a low-power mobile part built for Whiskey Lake, while the i5-5575R is a higher-TDP desktop chip from the Broadwell era. Benchmark data shows the newer mobile processor consistently outperforms the older desktop part across every tested workload, despite the i5-5575R's higher base clock and larger thermal envelope.

FAQ

Q: Which processor has the higher average benchmark score?

A: The Intel Core i7-8665U averages 1513 points, while the Intel Core i5-5575R averages 1478 points. The i7-8665U sits 0.7% below the Intel Pentium Gold G7400E (1524) and 0.9% above the Intel Core i3-8100T (1500), while the i5-5575R sits 0.4% below the Intel Core i5-7500T (1483) and 0.4% above the Intel Core i7-4710HQ (1473).

Q: How do they compare in multi-core Cinebench R23 performance?

A: The i7-8665U scores 5232 in Cinebench R23 multi-core, which is 21% higher than the i5-5575R's 4324. This is the largest absolute margin in the head-to-head tests, reflecting the i7's 8 threads versus the i5's 4 threads.

Q: What is the single-core performance gap?

A: In Cinebench R23 single-core, the i7-8665U scores 738 versus 610 for the i5-5575R, a 21% advantage. The same pattern holds in R20 (309 vs 256, 20.7% delta) and R15 (74 vs 61, 21.3% delta).

Q: Do both processors occupy the same performance percentile?

A: Yes, both the i7-8665U and the i5-5575R sit at the 38th percentile among all CPUs in the database. Despite different architectures and market segments, their overall standing relative to the broader CPU landscape is identical.

Q: What is the memory bandwidth difference?

A: The i7-8665U supports 38.4 GB/s of memory bandwidth, while the i5-5575R offers 29.9 GB/s. Both use dual-channel memory buses, but the i7 supports both DDR3 and DDR4, whereas the i5 only supports DDR3.

Q: Which chip has the larger die size?

A: The i5-5575R has a die size of 182 mm², while the i7-8665U's die size is not listed in the data. The i5's larger die reflects its desktop-oriented design with Iris Pro Graphics 6200.

Architecture Differences

The i7-8665U is built on Whiskey Lake, a refinement of Intel's 14 nm process, while the i5-5575R uses the older Broadwell architecture, also on 14 nm. Both chips are manufactured by Intel, but they target fundamentally different market segments: the i7 is a mobile part (BGA 1528 socket) with a 15 W TDP, while the i5 is a desktop part (BGA 1364 socket) with a 65 W TDP.

The core configuration differs sharply. The i7-8665U offers 4 cores and 8 threads thanks to Hyper-Threading, whereas the i5-5575R has 4 cores and 4 threads with no simultaneous multithreading. This thread advantage is likely the primary driver behind the i7's consistent multi-core wins. Cache allocation also favors the i7: it has 8 MB of shared L3 cache versus 4 MB on the i5, though both share identical per-core L1 (64 KB) and L2 (256 KB) caches.

Clock speeds tell a different story. The i5-5575R has a higher base clock at 2.80 GHz versus 1.90 GHz on the i7, but the i7's boost clock reaches 4.80 GHz versus 3.30 GHz on the i5. This aggressive boost capability, combined with the newer architecture, explains why the i7 wins in single-core tests despite the i5's base-clock advantage.

The integrated graphics differ substantially: the i7 uses UHD Graphics 620, while the i5 uses Iris Pro Graphics 6200. The i5's desktop orientation is further reflected in its larger die size of 182 mm², suggesting more on-die resources, though the i7's memory bandwidth (38.4 GB/s) exceeds the i5's (29.9 GB/s). The i7 also supports DDR4 memory in addition to DDR3, giving it more flexibility in system configuration.

The i7-8665U was released on 2018-09-30 and is marked as end-of-life, while the i5-5575R was released on 2015-05-14 and remains active in production. The i5's longevity suggests it found a niche in embedded or specialized desktop applications, despite being three years older.

Head-to-Head Benchmarks

The head-to-head results are unambiguous: the i7-8665U wins all six benchmark comparisons. The largest margin comes in Cinebench R15 multi-core, where the i7 scores 527 against the i5's 435, a 21.1% delta. This pattern repeats across the entire Cinebench suite, with deltas clustering tightly between 20.7% and 21.3%.

In Cinebench R20, the i7 scores 2197 multi-core and 309 single-core, versus 1816 and 256 for the i5, representing 21% and 20.7% advantages respectively. The R23 results are nearly identical in percentage terms: 5232 vs 4324 (21%) for multi-core and 738 vs 610 (21%) for single-core. The consistency of these deltas across different Cinebench versions suggests the performance gap is structural rather than workload-specific.

The single-core tests are particularly telling. The i5's higher base clock (2.80 GHz) does not translate into a win because the i7's boost clock reaches 4.80 GHz, a full 1.5 GHz higher than the i5's 3.30 GHz maximum. This boost advantage, combined with the newer Whiskey Lake microarchitecture, gives the i7 a 21.3% lead in R15 single-core (74 vs 61) and a 20.7% lead in R20 (309 vs 256).

The i5-5575R does have one benchmark not present in the i7's data: Geekbench results showing 3247 multi-core and 1072 single-core. However, since the i7 has no Geekbench scores in the pack, no direct comparison can be made. The i5's nearest rivals in the overall database include the Intel Core i5-7500T (1483, 0.4% higher) and the Intel Core i7-4710HQ (1473, 0.4% lower), placing it in a tight cluster around the 1478 average.

The Verdict

The data strongly favors the i7-8665U for anyone prioritizing raw compute performance. It wins every head-to-head benchmark by roughly 21%, which is a substantial margin for processors in the same performance percentile. The i7's 8 threads and 8 MB of L3 cache are clear advantages over the i5's 4 threads and 4 MB of L3 cache, and its 4.80 GHz boost clock crushes the i5's 3.30 GHz ceiling.

The i5-5575R's strengths are not in the benchmark numbers but in its status and configuration. It is an active production part, while the i7 is end-of-life. The i5 also offers a higher base clock (2.80 GHz) and a larger die (182 mm²), which may indicate better sustained performance under constant load, though the benchmarks do not reflect this. Its Iris Pro Graphics 6200 may be more capable than the i7's UHD Graphics 620, but no graphics benchmarks are available to confirm this.

For a user choosing between these two, the i7-8665U is the obvious pick for computational tasks. The data shows no scenario where the i5 wins, and the i7's memory bandwidth advantage (38.4 GB/s vs 29.9 GB/s) further cements its position. However, the i5's active production status and desktop socket (BGA 1364) may make it more suitable for long-term embedded designs where the i7's mobile socket (BGA 1528) and end-of-life status could be drawbacks.

Specification Differences

The two processors differ in nearly every specification category. The i7-8665U has 8 threads versus 4 on the i5-5575R, a 4-core difference in thread count despite both having 4 physical cores. Base clocks differ by 0.90 GHz (1.90 GHz vs 2.80 GHz), but boost clocks differ by 1.50 GHz (4.80 GHz vs 3.30 GHz), strongly favoring the i7.

Thermal design power is vastly different: the i7 draws 15 W versus 65 W for the i5, making the i7 far more power-efficient, though this comes with a lower base clock. The i7 uses a BGA 1528 socket, while the i5 uses BGA 1364, meaning they are not interchangeable in any system. The i7 supports both DDR3 and DDR4 memory at 38.4 GB/s bandwidth, while the i5 only supports DDR3 at 29.9 GB/s.

Cache sizes differ: the i7 has 8 MB shared L3 cache versus 4 MB on the i5, with identical per-core L1 and L2 caches. The i7's integrated graphics are UHD Graphics 620, while the i5 uses Iris Pro Graphics 6200. The i7 was released on 2018-09-30 with a launch MSRP of $409, while the i5 was released on 2015-05-14 with a launch MSRP of $265. The i7 is end-of-life; the i5 is active. The i5 has a listed die size of 182 mm²; the i7's die size is not provided. Both use PCIe Gen 3 with 16 CPU lanes, and neither supports ECC memory or an unlocked multiplier.

Where Each One Wins

The i7-8665U wins every benchmark category in the head-to-head comparison, totaling 6 wins out of 6. Its strongest showing is in multi-core workloads, where the 21.1% R15 delta and 21% R23 delta highlight the benefit of 8 threads. The i7 also dominates single-core tests, with a 21.3% lead in R15, making it the better choice for lightly-threaded applications like web browsing or office productivity that rely on high boost clocks.

The i5-5575R wins in no benchmark category, but it has qualitative advantages that the data cannot capture. Its active production status means it remains available for new designs, while the i7 is end-of-life. Its 65 W TDP and 2.80 GHz base clock suggest it can sustain higher continuous clock speeds without relying on boost, which may be preferable for always-on server or industrial workloads where power draw is less of a concern than consistent performance. Its Iris Pro Graphics 6200 may also offer better GPU compute, though no benchmarks verify this.

In terms of use-cases, the i7-8665U is suited for thin-and-light laptops where its 15 W TDP and 4.80 GHz boost deliver maximum responsiveness on battery power. The i5-5575R, with its 65 W TDP and desktop socket, is better suited for fan-cooled compact desktops or embedded systems where the higher base clock and active production status matter more than peak benchmark scores. The data's verdict is clear: for raw compute, choose the i7; for longevity and sustained base-clock operation, the i5 has its niche.