Intel Core i3-8145U vs Intel Core i7-870 Comparison

The Intel Core i7-870 is a 2009-era desktop processor built on the 45 nm Nehalem architecture, while the Intel Core i3-8145U is a 2018 mobile chip on the 10 nm Whiskey Lake architecture. The data shows a decisive performance shift: the i3-8145U wins all five shared Cinebench benchmarks, with margins ranging from 15.6% to 15.9% in the multi-core and single-core tests. However, the i7-870 counters with double the core count, double the thread count, twice the L3 cache, and a 95 W TDP versus the i3-8145U's 15 W TDP. This creates a fascinating split where the older, more power-hungry desktop part loses every compute race but offers architectural advantages that the benchmark scores do not capture.

Where Each One Wins

The Intel Core i3-8145U wins in every measurable compute benchmark in this comparison. In Cinebench R15 multi-core, it scores 322 versus the i7-870's 271, a 15.8% lead. In Cinebench R20 multi-core, the i3-8145U posts 1342 against 1132, a 15.6% advantage. The single-core tests follow the same pattern: R20 single-core shows 189 versus 159 (15.9% ahead), and R23 single-core shows 451 versus 380 (15.7% ahead). The i3-8145U also wins the R23 multi-core test with 3196 versus 2697, another 15.6% margin. These results indicate that the newer mobile chip delivers consistently higher throughput despite having only two cores and four threads.

The i7-870's wins are structural rather than benchmark-based. It has four cores and eight threads, matching double the i3-8145U's two cores and four threads. Its L3 cache is 8 MB shared, twice the i3-8145U's 4 MB shared. The i7-870 also supports DDR3 memory, while the i3-8145U uses DDR4 with a rated memory bandwidth of 38.4 GB/s. The i7-870 has no integrated graphics, whereas the i3-8145U includes UHD Graphics 620. For workloads that scale with core count and cache capacity, the i7-870's specifications suggest potential advantages, but the benchmark data shows the i3-8145U overcoming those structural differences in every tested scenario.

The i3-8145U also wins on platform features: it supports PCIe Gen 3 with 16 lanes, while the i7-870 is limited to PCIe Gen 2 with 16 lanes. The i3-8145U's memory bandwidth of 38.4 GB/s is explicitly listed, whereas the i7-870 has no listed memory bandwidth figure. In terms of production status, both are end-of-life, but the i3-8145U's launch MSRP is $281, a figure stated once here for reference.

FAQ

Q: Which processor has more cores and threads?

A: The Intel Core i7-870 has four cores and eight threads. The Intel Core i3-8145U has two cores and four threads.

Q: What is the performance difference in multi-core benchmarks?

A: The i3-8145U leads in all multi-core tests. In Cinebench R15 multi-core, it scores 322 versus 271 (15.8% ahead). In R20 multi-core, it scores 1342 versus 1132 (15.6% ahead). In R23 multi-core, it scores 3196 versus 2697 (15.6% ahead).

Q: How do the single-core scores compare?

A: The i3-8145U wins both single-core tests. In R20 single-core, it scores 189 versus 159 (15.9% ahead). In R23 single-core, it scores 451 versus 380 (15.7% ahead).

Q: What are the TDP differences?

A: The i7-870 has a 95 W TDP, while the i3-8145U has a 15 W TDP. This is a major difference in power consumption and thermal output.

Q: Do these processors support the same memory type?

A: No. The i7-870 supports DDR3 memory, while the i3-8145U supports DDR4 memory with a rated bandwidth of 38.4 GB/s.

Q: What is the release date gap between them?

A: The i7-870 was released on September 7, 2009. The i3-8145U was released on September 30, 2018. That is a nine-year gap.

Head-to-Head Benchmarks

The head-to-head results are unambiguous: the i3-8145U wins all five shared benchmarks. The largest single margin is in Cinebench R20 single-core, where the i3-8145U scores 189 against the i7-870's 159, a 15.9% difference. The R15 multi-core test shows the i3-8145U at 322 versus 271, a 15.8% lead. The R20 multi-core test shows 1342 versus 1132, a 15.6% margin. The R23 multi-core test shows 3196 versus 2697, also a 15.6% margin. The R23 single-core test shows 451 versus 380, a 15.7% difference.

These margins are remarkably consistent, ranging only from 15.6% to 15.9%. This consistency suggests a systematic advantage for the i3-8145U across both single-threaded and multi-threaded workloads, rather than a workload-specific quirk. The i7-870's additional cores and threads do not translate into any benchmark win; the i3-8145U's higher boost clock of 3.90 GHz versus 3.60 GHz, combined with a more modern architecture, appears to overcome the core-count deficit.

The average benchmark scores reinforce this picture. The i7-870 has an avgBenchmarkScore of 928, while the i3-8145U has an avgBenchmarkScore of 941. Both sit at the 25th percentile among all CPUs. The nearest rivals for the i7-870 include the Intel Core i5-4288U with an avgScore of 927 (0.1% delta), the Intel Core i3-4350T with 926 (0.2% delta), and the Intel Celeron G6900TE with 925 (0.4% delta). The i3-8145U's nearest rivals include the Intel Core i7-2715QE with 942 (-0.1% delta), the AMD Athlon X4 860K with 943 (-0.2% delta), and the Intel Core i5-4330M with 938 (0.3% delta). These rival scores show both CPUs clustering within a narrow band around the 925-945 range.

Specification Differences

The two processors differ in nearly every core specification. The i7-870 has four cores and eight threads, while the i3-8145U has two cores and four threads. Base clocks are 2.93 GHz for the i7-870 versus 2.10 GHz for the i3-8145U. Boost clocks are 3.60 GHz for the i7-870 versus 3.90 GHz for the i3-8145U. The TDP difference is stark: 95 W for the i7-870 versus 15 W for the i3-8145U.

The sockets are incompatible: the i7-870 uses Intel Socket 1156, while the i3-8145U uses Intel BGA 1528. The i7-870 is a desktop part, while the i3-8145U is a mobile part. The i7-870 has no integrated graphics, while the i3-8145U includes UHD Graphics 620. Memory support differs: DDR3 for the i7-870, DDR4 for the i3-8145U. The i3-8145U has a listed memory bandwidth of 38.4 GB/s, while the i7-870 has no listed bandwidth. PCIe support differs: Gen 2 for the i7-870, Gen 3 for the i3-8145U. The i7-870 has a die size of 296 mm² and 774 million transistors, while the i3-8145U has no listed die size or transistor count.

Architecture Differences

The i7-870 is built on Nehalem architecture with the codename Lynnfield, using a 45 nm process node. The i3-8145U uses Whiskey Lake architecture with the codename Whiskey Lake-U, on a 10 nm process node. The i7-870's generation is "Core i7 (Lynnfield)", while the i3-8145U's generation is "Core i3 (Whiskey Lake)". The i7-870 has an 8 MB shared L3 cache, while the i3-8145U has a 4 MB shared L3 cache. Both have identical L1 cache of 64 KB per core and L2 cache of 256 KB per core.

The i7-870 has a larger die size at 296 mm² and a transistor count of 774 million, reflecting the older, larger process. The i3-8145U has no listed die size or transistor count, indicating the die-shrink benefits of the 10 nm node. The i7-870's foundry is Intel, as is the i3-8145U's. Neither processor has ECC memory support, and neither has an unlocked multiplier. The i7-870's part number is SLBJG, while the i3-8145U lists multiple part numbers: SRFFZ, SRD1W, and SRD1V.

The Verdict

The benchmark data points decisively toward the Intel Core i3-8145U for all compute workloads tested. It wins every single Cinebench benchmark, with margins between 15.6% and 15.9%. The i3-8145U achieves this with half the cores, half the threads, and a TDP of 15 W versus 95 W. The i3-8145U also offers integrated graphics, PCIe Gen 3 support, and DDR4 memory with a rated bandwidth of 38.4 GB/s. Its launch MSRP is $281.

The i7-870 retains structural advantages: four cores, eight threads, 8 MB of L3 cache, and a larger die size of 296 mm². These specifications suggest potential strengths in highly parallel workloads that do not appear in the Cinebench tests. However, the benchmark results show the i3-8145U outperforming the i7-870 even in multi-core tests, indicating that the newer architecture and higher boost clock of 3.90 GHz overcome the core-count deficit.

For a buyer choosing between these two end-of-life processors, the data supports the i3-8145U for any task involving the tested Cinebench workloads. The i7-870's only advantages are its core and cache specifications, which do not translate into benchmark wins. The i3-8145U's lower TDP, integrated graphics, and modern platform features make it the more capable processor in the data. The i7-870 would be chosen only by someone prioritizing core count and cache capacity over all measured performance outcomes.