Intel Core i5-6600T vs Intel Core i7-8665U Comparison

Head-to-Head Benchmarks

The benchmark data presents a clear and consistent picture across all recorded workloads. The Intel Core i7-8665U wins every single head-to-head comparison in the database, taking all six recorded tests. The Intel Core i5-6600T does not record a single victory in any of the shared benchmarks.

In the Cinebench R15 multi-core test, the i7-8665U scores 527 against the i5-6600T's 478, a delta of -9.3% from the perspective of the i5-6600T. The single-core R15 result follows the same pattern, with the i7-8665U at 74 and the i5-6600T at 67, a -9.5% delta. The margin is nearly identical across the entire suite, which suggests the performance gap is structural rather than workload-specific.

Moving to the newer Cinebench R20 suite, the i7-8665U posts 2197 in multi-core versus 1992 for the i5-6600T, again a -9.3% delta. In single-core R20, the i7-8665U reaches 309 while the i5-6600T manages 280, a -9.4% delta. The consistency of these margins is notable; the delta hovers between -9.3% and -9.5% across all six tests.

The Cinebench R23 results reinforce this pattern. The i7-8665U scores 5232 in multi-core against 4745 for the i5-6600T, a -9.3% delta. In single-core R23, the i7-8665U posts 738 versus 669, also -9.3%. No test shows the margin shrinking or expanding beyond a narrow band, indicating a uniform performance advantage that scales across both single-threaded and multi-threaded workloads.

The Geekbench results are only recorded for the i5-6600T in this database, with a multi-core score of 3104 and a single-core score of 1172. The i7-8665U does not have Geekbench entries in the recorded data, so no direct head-to-head comparison is possible for that particular suite. The available Cinebench data, however, provides comprehensive coverage of both processors across three generations of the rendering workload.

The average benchmark score for the i5-6600T is 1563, while the i7-8665U averages 1513. This is interesting because it appears to contradict the head-to-head results. The explanation lies in the different benchmark sets used for each processor. The database records Geekbench scores for the i5-6600T, which are not present for the i7-8665U. The average is computed across each processor's own benchmark list, not the shared tests. The i7-8665U's average is dragged down by the absence of Geekbench scores, while the i5-6600T benefits from including those higher-scoring results.

Both processors sit at nearly identical percentiles relative to all CPUs in the database. The i5-6600T records a percentile of 39, and the i7-8665U records 38. This places both in the lower-middle tier of all processors, a positioning that aligns with their comparable average scores.

Where Each One Wins

The i7-8665U wins every recorded head-to-head benchmark. There is no category in the shared data where the i5-6600T takes the lead. The multi-core tests show the i7-8665U ahead by roughly 9% in R15, R20, and R23. The single-core tests show the same approximate margin. This uniform advantage means the i7-8665U is the better choice for both heavily threaded rendering workloads and lightly threaded tasks.

For the i5-6600T, the wins are limited to benchmarks that are not shared with the i7-8665U. Specifically, the Geekbench multi-core score of 3104 and single-core score of 1172 are recorded for this processor but not for its rival. In the absence of a Geekbench result for the i7-8665U, the database cannot determine which processor would win that particular suite. The i5-6600T also carries the UHD Graphics 530 integrated GPU, while the i7-8665U uses the UHD Graphics 620. Neither integrated graphics performance is quantified in the database, so no comparison can be made on that front.

The i5-6600T operates at a base clock of 2.70 GHz with a boost clock of 3.50 GHz, a 35 W TDP, and a desktop socket. The i7-8665U runs at a base clock of 1900.00 MHz (which converts to 1.90 GHz in standard notation) with a boost clock of 4.80 GHz and a 15 W TDP. The i7-8665U's lower power envelope makes it the more efficient option in thermal terms, though the database records no direct efficiency metric.

The i5-6600T supports DDR3 and DDR4 memory with dual-channel access and a recorded bandwidth of 34.1 GB/s. The i7-8665U also supports DDR3 and DDR4 with dual-channel access and a higher recorded bandwidth of 38.4 GB/s. This gives the i7-8665U a memory bandwidth advantage of 4.3 GB/s, which contributes to its multi-core performance in memory-sensitive workloads.

For users running Cinebench R15, R20, R23, the i7-8665U is ahead in every iteration of that suite. For users running Geekbench, the i5-6600T has recorded scores but no comparison exists. The database cannot award a win in Geekbench to either processor.

The Verdict

The data points to the Intel Core i7-8665U as the stronger processor in every measurable shared workload. It leads by margins between 9.3% and 9.5% across six Cinebench tests, covering both single-core and multi-core scenarios. The i5-6600T has no head-to-head wins in the recorded data.

The i7-8665U achieves this with a 15 W TDP, while the i5-6600T draws 35 W. It also provides 8 threads versus 4, 8 MB of shared L3 cache versus 6 MB, and a higher memory bandwidth of 38.4 GB/s versus 34.1 GB/s. The boost clock of 4.80 GHz exceeds the i5-6600T's 3.50 GHz by a substantial margin. The base clock, however, is lower at 1900.00 MHz versus 2.70 GHz, which is typical for low-power mobile processors that rely on boosting.

The i5-6600T does offer a socketed desktop form factor (Intel Socket 1151) versus the i7-8665U's BGA 1528 package. It has a larger recorded die size of 177 mm², where the i7-8665U does not list a die size in the database. The i5-6600T also has a lower launch MSRP of $213. The i7-8665U carries a launch MSRP of $409.

The i7-8665U sits at percentile 38 among all CPUs, and the i5-6600T sits at 39, nearly identical positioning. The average scores of 1513 and 1563 respectively place them close together in the database hierarchy. The i7-8665U's nearest rivals include the Intel Pentium Gold G7400E at an average score of 1524 with a delta of -0.7%, the Intel Core i5-4670S at 1526 with -0.9%, the Intel Core i5-7440HQ at 1527 with -0.9%, and the Intel Core i3-990T at 1500 with 0.9%. The i5-6600T's nearest rivals include the Intel Core i3-8300 at 1564 with -0.1% delta, the AMD Ryzen 3 1300X at 1300 with 0.1% delta, the AMD Opteron 6276 at 1560 with 0.2%, and the Intel Core i3-1115G4E at 1559 with 0.3%.

FAQ

Q: Which processor wins the Cinebench R23 multi-core test?

A: The Intel Core i7-8665U wins with a score of 5232 against 4745 for the Intel Core i5-6600T, a delta of -9.3% for the i5-6600T.

Q: What is the core and thread count difference between the two processors?

A: Both have 4 cores, but the i7-8665U has 8 threads, and the i5-6600T has 4 threads.

Q: How does the memory bandwidth compare between the i5-6600T and i7-8665U?

A: The i7-8665U records 38.4 GB/s of memory bandwidth, and the i5-6600T records 34.4 GB/s.

Q: What is the TDP difference between the two processors?

**A: The i5-6600T has a TDP of 35 W, and the i7-8665U has a TDP of 15 W.

Q: What are the integrated graphics on each processor?

A: The i5-6600T uses UHD Graphics 530, and the i7-8665U uses UHD Graphics 620.

Q: What is the socket type for each processor?

A: The i5-6600T uses Intel Socket 1151, and the i7-8665U uses Intel BGA 1528.

Q: What is the process node for both processors?

A: Both the i5-6600T and i7-8665U are built on Intel's 14 nm process node.

Q: Which processor has a higher boost clock speed in the recorded data?

A: The i7-8665U has a boost clock of 4.80 GHz, and the i5-6600T has a boost clock of 3.50 GHz.

Architecture Differences

The architecture gap between these two processors spans several generations and market segments. The i5-6600T comes from the Skylake architecture, released with a Core i5 generation label. The i7-8665U comes from Whiskey Lake, released with a Core i7 (Whiskey Lake) label, and specifically the Whiskey Lake-U variant. Both are built on the 14 nm process node at Intel's foundry.

The desktop and mobile split shows in the sockets: the i5-6600T uses Intel Socket 1151, while the i7-8665U uses Intel BGA 1528, a ball grid array package. The i7-8665U is designed for mobile systems, while the i5-6600T is a desktop processor.

The memory support is identical in type, with DDR3 and DDR4 support, both dual-channel. The i5-6600T records a memory bandwidth of 34.1 GB/s, while the i7-8665U records 38.1 GB/s. The i5-6600T has a die size of 177 mm², and the i7-8665U lists no die size in the database. Both have 4 cores and 64 KB L1 cache per core, 256 KB L2 cache per core, and shared L3 cache, with the L3 at 6 MB for the i5-6600T and 8 MB for the i7-8665U.

Both support PCIe Gen 3 with 16 lanes from the CPU, and both have ECC memory support disabled. Neither has an unlocked multiplier. The i5-6600T uses integrated graphics UHD Graphics 530, and the i7-8665U uses UHD Graphics 620. The i5-6600T has release date of 2015-07-01, and the i7-8665U has release date of 2018-09-30. The i5-6600T is listed as End-of-life, as is the i7-8665U. The i5-6600T part number is SR2L9 and the i7-8665U part number is SRF9W.