Intel Core i5-6600K vs Intel Core i5-8305G Comparison

The Intel Core i5-8305G and the Intel Core i5-6600K represent two distinct interpretations of Intel’s 14nm era: a mobile processor with an integrated Radeon graphics package versus a desktop part designed for enthusiasts. Benchmark data shows a fascinating split, with the newer mobile chip sweeping all Cinebench tests while the older desktop chip counters decisively in Geekbench. This head-to-head reveals that raw core count and clock speed tell only part of the story; software optimization and platform intent matter just as much.

Head-to-Head Benchmarks

The most striking pattern in the data is the complete dominance of the Intel Core i5-8305G across the entire Cinebench suite. In Cinebench R15 multi-core, the 8305G scores 578 against the 6600K’s 540, a 7% advantage. The single-core R15 result follows suit, with the 8305G at 81 versus 76, a 6.6% lead. This trend continues into newer Cinebench versions: R20 multi-core shows 2410 versus 2252 (7% ahead), and R20 single-core shows 340 versus 317 (7.3% ahead). The R23 results are equally lopsided, with the 8305G winning multi-core 5739 to 5363 and single-core 810 to 757, both representing a consistent 7% margin.

The consistency of that ~7% delta across all Cinebench tests is curious. It suggests a structural advantage in how the 8305G handles these workloads, likely tied to its hyper-threading capability, which the 6600K lacks. The 8305G has 8 threads while the 6600K has only 4, and Cinebench scales well with additional threads. Yet the single-core wins are nearly as large, which points to the 8305G’s architecture extracting more instructions per clock in this specific benchmark environment, despite the 6600K having a higher boost clock.

However, the Geekbench results tell a completely different story. The Intel Core i5-6600K wins multi-core with a score of 3856 versus 3536, an 8.3% advantage for the desktop part. The single-core gap is even wider: 1363 versus 1150, a 15.6% lead for the 6600K. This is a dramatic reversal. The data implies that Geekbench’s workload composition favors the 6600K’s higher base clock (3.50 GHz versus 2.80 GHz) and higher boost clock (3.90 GHz versus 3.80 GHz), and possibly its unlocked multiplier allows more aggressive sustained frequencies. The 8305G’s lower clocks, designed to fit within a 65W TDP for mobile use, become a liability in this test.

Averaging everything out, the 8305G takes 6 wins out of 8 head-to-head benchmarks, but the two losses are significant. The average benchmark scores are remarkably close: the 8305G averages 1831 while the 6600K averages 1816, a difference of less than 1%. Both processors sit at the 42nd percentile among all CPUs, placing them in the same performance tier overall. The nearest rivals for the 8305G include the AMD Ryzen 5 4600U at 1832 (0% delta) and Intel Xeon E5-2608L v3 at 1830 (0% delta), while the 6600K’s rivals include the Intel Xeon E3-1505M v5 at 1817 (-0.1% delta) and AMD Ryzen 5 PRO 4650U at 1810 (0.3% delta). The data suggests these two processors are peers in aggregate, despite their divergent benchmark profiles.

Architecture Differences

The architectural split between these chips explains much of the benchmark behavior. The Intel Core i5-8305G uses the Kaby Lake architecture, specifically the Kaby Lake G codename, built on Intel’s 14 nm process node. It features 4 cores and 8 threads, a base clock of 2.80 GHz, and a boost clock of 3.80 GHz. The cache hierarchy is straightforward: 64 KB of L1 per core, 256 KB of L2 per core, and 6 MB of shared L3. It supports DDR4 memory, does not support ECC, and is not multiplier unlocked. It is a mobile processor (market segment "Mobile") with an integrated Radeon RX Vega M GL GPU, and it remains in active production. Its release date is January 31, 2018.

The Intel Core i5-6600K, by contrast, uses the older Skylake architecture, also on 14 nm. It has 4 cores but only 4 threads — no hyper-threading — with a base clock of 3.50 GHz and a boost clock of 3.90 GHz. Its cache is identical in structure: 64 KB L1 per core, 256 KB L2 per core, and 6 MB shared L3. However, it supports both DDR3 and DDR4 memory, has a dual-channel memory bus, and a memory bandwidth of 34.1 GB/s. It also offers PCIe Gen 3 with 16 lanes from the CPU. Its integrated graphics is HD Graphics 530, a much less capable GPU than the Radeon RX Vega M GL in the 8305G. It is a desktop processor, is end-of-life, was released on August 4, 2015, and has an unlocked multiplier for overclocking. Its launch MSRP was $242.

The TDP difference is stark: the 8305G draws 65W while the 6600K draws 91W. This explains why the mobile chip has lower clocks — it must fit in thermally constrained laptops. Yet the 8305G still manages to beat the 6600K in Cinebench, which suggests that hyper-threading and architectural refinements in Kaby Lake compensate for the clock deficit. The 6600K’s higher TDP and desktop socket (Intel Socket 1151) versus the 8305G’s BGA 2270 (soldered, non-upgradeable) reflect their different design goals.

FAQ

Q: Which processor has more threads, and does it matter?

A: The Intel Core i5-8305G has 8 threads while the Intel Core i5-6600K has 4 threads. The data shows the 8305G wins all Cinebench multi-core tests by 7%, which is likely attributable to this thread advantage, as Cinebench scales with parallel execution.

Q: Why does the Intel Core i5-6600K win Geekbench despite having fewer threads?

A: The 6600K wins Geekbench multi-core by 8.3% and single-core by 15.6%. Its higher base clock (3.50 GHz vs 2.80 GHz) and boost clock (3.90 GHz vs 3.80 GHz) give it a raw frequency advantage that Geekbench appears to reward more heavily than Cinebench does.

Q: Are these processors in the same performance tier?

A: Yes. Both sit at the 42nd percentile among all CPUs, and their average benchmark scores are 1831 for the 8305G and 1816 for the 6600K, a difference of only about 0.8%. Their nearest rivals overlap in score range.

Q: Which processor has better integrated graphics?

A: The Intel Core i5-8305G features Radeon RX Vega M GL graphics, while the Intel Core i5-6600K has HD Graphics 530. The data does not include graphics benchmarks, but the product specifications clearly indicate a more advanced GPU in the 8305G.

Q: Can the Intel Core i5-6600K be overclocked?

A: Yes. The 6600K has an unlocked multiplier, while the 8305G does not. The data does not provide overclocking results, but the specification difference means the 6600K can potentially exceed its stock boost clock of 3.90 GHz.

Q: Which processor is newer?

A: The Intel Core i5-8305G was released on January 31, 2018, while the Intel Core i5-6600K was released on August 4, 2015. The 8305G is also still in active production, whereas the 6600K is end-of-life.

The Verdict

The benchmark data presents a nuanced picture. For multi-threaded productivity workloads as measured by Cinebench, the Intel Core i5-8305G is clearly superior, winning every single test by a consistent 7% margin. Its 8 threads and Kaby Lake architecture deliver better scaling in these rendering tasks. The 8305G also offers a dramatically more capable integrated GPU with the Radeon RX Vega M GL, making it a better choice for compact systems or laptops where discrete graphics are not an option.

However, the Intel Core i5-6600K wins in Geekbench, particularly in single-core performance where it leads by 15.6%. This suggests it has an edge in lightly-threaded applications that are sensitive to clock speed. Its higher 91W TDP and desktop socket allow for sustained high frequencies, and its unlocked multiplier provides overclocking headroom that the 8305G entirely lacks. For users who prioritize raw clock speed and are willing to build a desktop system with discrete graphics, the 6600K remains competitive.

The aggregate scores are nearly identical, so the choice depends on workload. The data shows the 8305G wins 6 out of 8 benchmarks, but the two Geekbench losses are substantial. A user running Cinebench-style rendering will prefer the 8305G; a user running Geekbench-style mixed workloads will prefer the 6600K. The 6600K’s end-of-life status and higher TDP are drawbacks, but its overclocking capability and memory flexibility (DDR3 and DDR4) keep it relevant for certain builders.

Specification Differences

The two processors differ in several key specification fields. The Intel Core i5-8305G has 8 threads while the Intel Core i5-6600K has 4 threads. The base clock differs significantly: 2.80 GHz for the 8305G versus 3.50 GHz for the 6600K. The boost clock also differs, with the 8305G at 3.80 GHz and the 6600K at 3.90 GHz. The TDP is 65W for the 8305G and 91W for the 6600K. The socket types are entirely different: the 8305G uses Intel BGA 2270 (soldered) while the 6600K uses Intel Socket 1151 (LGA, replaceable).

The architecture generation differs (Kaby Lake-G vs Skylake), and the codenames differ (Kaby Lake G vs Skylake). The market segments are different: Mobile for the 8305G and Desktop for the 6600K. Production status differs: Active for the 8305G and End-of-life for the 6600K. Release dates are years apart: January 31, 2018 versus August 4, 2015. The 8305G has no launch MSRP listed, while the 6600K has a launch MSRP of $242. The 6600K has an unlocked multiplier, but the 8305G does not. The 6600K supports DDR3 in addition to DDR4, while the 8305G supports only DDR4. The 6600K has a listed memory bandwidth of 34.1 GB/s and PCIe Gen 3 with 16 lanes, while the 8305G has no memory bandwidth or PCIe lane data provided. The integrated graphics differ: Radeon RX Vega M GL for the 8305G versus HD Graphics 530 for the 6600K.

Where Each One Wins

The Intel Core i5-8305G wins in every Cinebench test across R15, R20, and R23, both multi-core and single-core. This indicates its strengths lie in CPU rendering workloads, particularly those that benefit from hyper-threading. The 7% consistent margin suggests a reliable advantage in threaded applications. Additionally, its Radeon RX Vega M GL integrated graphics make it the superior choice for systems without a discrete GPU, as the 6600K’s HD Graphics 530 is a much weaker integrated solution. The 8305G also wins on efficiency, with a 65W TDP versus 91W, making it suitable for thinner laptops or compact desktops.

The Intel Core i5-6600K wins in Geekbench multi-core by 8.3% and single-core by 15.6%. This points to its strengths in general-purpose computing tasks that favor higher clock speeds, such as everyday application responsiveness, gaming (when paired with a discrete GPU), and single-threaded productivity software. Its higher base and boost clocks give it a tangible performance edge in these scenarios. The unlocked multiplier further extends its winning potential for overclockers who can push clocks beyond stock, although the data does not quantify this. The 6600K’s socket 1151 also allows for CPU upgrades without changing the motherboard, a flexibility the soldered 8305G cannot offer.