Intel Core i7-3770S vs Intel Core i7-8665U Comparison

The Intel Core i7-8665U and Intel Core i7-3770S are both 4-core, 8-thread processors, but they represent vastly different eras and design goals for Intel. The data shows a remarkably close competition in raw compute benchmarks, despite the 8665U being a 15-watt mobile part and the 3770S a 65-watt desktop chip. Across the six shared Cinebench tests, the older 3770S wins five, but the margins are almost negligible, with the largest gap being just 0.6%. This creates a fascinating profile where architectural age is neutralized by power efficiency and clock speed differences.

Head-to-Head Benchmarks

The benchmark results indicate a near dead heat in multi-threaded workloads. In Cinebench R15 multi-core, the i7-3770S scores 529 against the i7-8665U's 527, a delta of -0.4% favoring the desktop part. The pattern repeats in Cinebench R20 multi-core, where the 3770S edges ahead with 2205 points versus 2197, again a -0.4% difference. Cinebench R23 multi-core shows the same story: the 3770S posts 5251 while the 8665U manages 5232, a -0.4% gap. These results suggest that the newer Whiskey Lake architecture's efficiency gains essentially cancel out the 3770S's higher base clock of 3.10 GHz versus 1.90 GHz, at least when both are allowed to boost.

Single-core performance is similarly tight. Cinebench R15 single-core is a perfect tie at 74 points for both chips, with the delta listed as 0% and the win technically awarded to the 8665U. In Cinebench R20 single-core, the 3770S takes the lead with 311 points against 309, a -0.6% difference. Cinebench R23 single-core follows the same pattern: 741 for the 3770S versus 738 for the 8665U, a -0.4% margin. The 8665U's higher boost clock of 4.80 GHz versus 3.90 GHz on the 3770S does not translate into a decisive single-core advantage; the older Ivy Bridge design holds its own, likely due to its higher sustained all-core clocks.

The overall win tally stands at 5 for the i7-3770S and 1 for the i7-8665U, but that single win is a tie. The average benchmark score further contextualizes this: the 8665U has an average score of 1513, while the 3770S sits at 1498. This means the 8665U is actually slightly ahead on average across all tests, despite losing the head-to-head Cinebench matchups. Both processors rank at the 38th percentile among all CPUs, placing them in the same performance tier. The nearest rivals for the 8665U include the Intel Pentium Gold G7400E (avg score 1524, delta -0.7%) and the Intel Core i5-4670S (avg score 1526, delta -0.9%), while the 3770S sits near the Intel Core i3-8100T (avg score 1500, delta -0.1%) and the Intel Core i5-4590S (avg score 1493, delta 0.4%).

Architecture Differences

The i7-8665U is built on Whiskey Lake, a 14 nm process, and belongs to the Core i7 (Whiskey Lake) generation. Its codename is Whiskey Lake-U, indicating a low-power mobile design. The i7-3770S, in contrast, uses Ivy Bridge on a 22 nm process, from the Core i7 (Ivy Bridge) generation. This generational gap is significant: the 8665U benefits from a smaller transistor node, which typically improves power efficiency and allows higher boost clocks within a lower thermal envelope.

Cache configurations are identical on paper: both have 64 KB of L1 per core, 256 KB of L2 per core, and 8 MB of shared L3 cache. The die size and transistor counts differ only in that the 3770S reports 1,400 million transistors on a 160 mm² die, while the 8665U does not have those figures listed. Memory support diverges: the 8665U supports both DDR3 and DDR4 with a memory bandwidth of 38.4 GB/s, whereas the 3770S only supports DDR3 and has no listed memory bandwidth figure. Both use dual-channel memory buses and PCIe Gen 3 with 16 lanes.

Integrated graphics differ substantially. The 8665U includes UHD Graphics 620, while the 3770S ships with Intel HD 4000. Neither chip supports ECC memory, and both have locked multipliers. The sockets are incompatible: the 8665U uses Intel BGA 1528, a soldered mobile socket, while the 3770S uses Intel Socket 1155 for desktop motherboards. The market segments confirm this split: mobile versus desktop. The 8665U was released on 2018-09-30, while the 3770S arrived on 2012-04-28, making the 3770S over six years older. The production status for the 8665U is listed as end-of-life, while the 3770S has no production status listed.

The Verdict

Strictly from the data, the i7-3770S is the faster processor in most compute benchmarks, winning five of six head-to-head tests. However, the margins are so small—all under 1%—that real-world performance would be indistinguishable in most workloads. The 3770S's advantage comes from its higher base clock of 3.10 GHz and its 65-watt TDP, which allows sustained performance without the thermal constraints of the 8665U's 15-watt design.

The i7-8665U, despite losing the head-to-head, has a higher average benchmark score of 1513 versus 1498 and a higher boost clock of 4.80 GHz. This suggests it can burst to higher single-thread speeds when needed, but cannot sustain them as effectively. The 8665U also supports DDR4 memory, which is a modern advantage, and includes newer integrated graphics in UHD Graphics 620.

For a desktop user with a Socket 1155 motherboard and DDR3 memory, the i7-3770S is the clear choice based on raw performance and the fact that it wins the majority of tests. For a mobile user needing a low-power chip, the i7-8665U is the only viable option given its BGA 1528 socket and 15-watt TDP. Neither chip is unlocked, so overclocking is off the table. The 38th percentile ranking for both chips indicates they are mid-pack performers today, not leaders.

FAQ

Q: Which processor is faster in multi-core Cinebench R23?

A: The Intel Core i7-3770S scores 5251 versus the Intel Core i7-8665U's 5232, a delta of -0.4% favoring the 3770S.

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

A: Yes, both have 4 cores and 8 threads.

Q: What is the average benchmark score for each chip?

A: The i7-8665U has an average score of 1513, while the i7-3770S has an average score of 1498.

Q: Which chip supports DDR4 memory?

A: Only the i7-8665U supports DDR4; the i7-3770S only supports DDR3.

Q: What is the TDP difference between the two?

A: The i7-8665U has a TDP of 15 watts, while the i7-3770S has a TDP of 65 watts.

Q: Which processor has a higher boost clock?

A: The i7-8665U has a boost clock of 4.80 GHz, compared to the i7-3770S's 3.90 GHz.

Where Each One Wins

The i7-3770S wins in sustained multi-threaded performance, as evidenced by its victories in Cinebench R15, R20, and R23 multi-core tests. It also wins in single-core Cinebench R20 and R23, though by tiny margins. Its higher base clock of 3.10 GHz and 65-watt TDP allow it to maintain performance over longer periods without throttling. This makes it suitable for desktop workloads where power draw is not a concern and consistent compute is required.

The i7-8665U wins in the efficiency and portability domain. Its 15-watt TDP is a fraction of the 3770S's 65 watts, making it suitable for thin-and-light laptops. It also supports DDR4 memory, which offers a more modern upgrade path, and its UHD Graphics 620 is a newer integrated graphics solution than the HD 4000. The 8665U's higher boost clock of 4.80 GHz gives it a theoretical edge in short bursts of single-threaded activity, even if the benchmark data does not reflect a decisive advantage. The 8665U also has the higher average benchmark score, suggesting it performs better across a broader range of tests not covered in the head-to-head list.

Specification Differences

The two processors differ in several key specifications. The i7-8665U has a base clock of 1900.00 MHz and a boost clock of 4.80 GHz, while the i7-3770S has a base clock of 3100.00 MHz and a boost clock of 3.90 GHz. TDP is drastically different: 15 watts for the 8665U versus 65 watts for the 3770S. Sockets are incompatible: Intel BGA 1528 for the 8665U versus Intel Socket 1155 for the 3770S.

The process nodes differ: 14 nm for the 8665U versus 22 nm for the 3770S. Memory support is broader on the 8665U, which handles DDR3 and DDR4, while the 3770S only supports DDR3. The 8665U lists a memory bandwidth of 38.4 GB/s, while the 3770S does not list one. Integrated graphics are UHD Graphics 620 on the 8665U and Intel HD 4000 on the 3770S. The market segment is mobile for the 8665U and desktop for the 3770S. Release dates are 2018-09-30 for the 8665U and 2012-04-28 for the 3770S. The 8665U has a listed launch MSRP of $409, while the 3770S does not have a launch MSRP listed. Transistor count and die size are only listed for the 3770S: 1,400 million transistors on a 160 mm² die. The part numbers are SRF9W for the 8665U and SR0PN for the 3770S.