Intel Core i5-8400T vs Intel Core i7-5775R Comparison

FAQ

Q: Which processor has more cores and threads?

A: The Intel Core i5-8400T has 6 cores and 6 threads, while the Intel Core i7-5775R has 4 cores and 8 threads.

Q: What is the difference in TDP between the two chips?

A: The Intel Core i5-8400T has a TDP of 35 watts, while the Intel Core i7-5775R has a TDP of 65 watts.

Q: Which CPU supports DDR4 memory?

A: The Intel Core i5-8400T supports DDR4 memory, whereas the Intel Core i7-5775R supports DDR3 memory.

Q: Which processor has a higher single-core Geekbench score?

A: The Intel Core i7-5775R scores 1218 in Geekbench single-core, compared to 1100 for the Intel Core i5-8400T, a 9.7% advantage.

Q: How do the two chips compare in average benchmark score?

A: The Intel Core i7-5775R has an average benchmark score of 2031, while the Intel Core i5-8400T has an average benchmark score of 2001. Both sit at the 45th percentile among all CPUs.

Q: Which processor has a larger L3 cache?

A: The Intel Core i5-8400T has 9 MB of shared L3 cache, while the Intel Core i7-5775R has 6 MB of shared L3 cache.

Architecture Differences

The Intel Core i5-8400T is built on the Coffee Lake architecture and uses a 14 nm process node, with a die size of 154 mm². It features 6 physical cores without hyper-threading, yielding 6 threads. The Intel Core i7-5775R is based on the older Broadwell architecture, also on a 14 nm process, but with a larger die size of 182 mm². It packs 4 physical cores with hyper-threading, producing 8 threads.

The cache hierarchies differ notably. The i5-8400T carries 64 KB of L1 per core and 256 KB of L2 per core, then moves to a 9 MB shared L3 cache. The i7-5775R also has 64 KB L1 per core and 256 KB L2 per core, but its shared L3 is smaller at 6 MB. In multi-threaded workloads, the i5's extra two physical cores offset the i7's thread advantage, while the i7 leans on higher clock speeds.

Memory support separates the two clearly. The i5-8400T uses DDR4 memory with dual-channel support and a theoretical memory bandwidth of 42.7 GB/s. The i7-5775R uses DDR3 memory, also dual-channel, with a lower theoretical bandwidth of 29.9 GB/s. Both lack ECC memory support.

The integrated graphics differ as well. The i5-8400T includes UHD Graphics 630, while the i7-5775R includes Iris Pro Graphics 6200. The i7's integrated GPU is generally more capable for graphics tasks, though no benchmark data in this comparison covers that directly.

Both processors use PCIe Gen 3 with 16 lanes from the CPU. The i5-8400T uses the Intel Socket 1151 platform, while the i7-5775R uses the BGA 1364 socket, meaning the latter is soldered rather than socketed. Neither chip has an unlocked multiplier. The i5-8400T was released in 2018, the i7-5775R in 2015, and both are marked end-of-life in the database.

Where Each One Wins

The Intel Core i7-5775R wins 7 out of 8 head-to-head benchmark comparisons. Its victories span every Cinebench test (R15, R20, R23) in both single-core and multi-core, plus Geekbench single-core. The i7-5775R wins by 1.1% to 1.2% in Cinebench tests, with its single-core Geekbench margin being the largest at 9.7%. This pattern points to higher clock speeds: the i7-5775R boosts to 3.80 GHz boost, compared to the i5-8400T's 3.30 GHz boost, and its base clock sits at 3.30 GHz versus 1700 MHz for the i5-8400T.

The Intel Core i5-8400T wins exactly one test: Geekbench multi-core, scoring 4011 against 3996, a 0.4% edge. That single win shows the value of 6 physical cores. In workloads that scale well across cores and are not heavily dependent on memory bandwidth, the i5-8400T can outperform the i7-5775R despite the latter's higher thread count and clock speed advantage.

For users running diverse applications that rely on single-thread performance, the i7-5775R is the safer choice. For applications that prefer more physical cores over hyper-threading, the i5-8400T provides a narrow winning margin in at least one major benchmark suite.

Specification Differences

The clock speed gap is the defining factor. The i5-8400T base clock is 1700 MHz, boost clock 3.30 GHz, TDP 35 watts, socket Intel Socket 1151, architecture Coffee Lake, process node 14 nm, die size 154 mm², L3 cache 9 MB (shared), memory support DDR4, memory bandwidth 42.7 GB/s, integrated graphics UHD Graphics 630, release date 2018-04-01, launch MSRP $182, part number SR3X6.

The i7-5775R base clock is 3.30 GHz, boost clock 3.80 GHz, TDP 65 watts, socket Intel BGA 1364, architecture Broadwell, process node 14 nm, die size 182 mm², L3 cache 6 MB (shared), memory support DDR3, memory bandwidth 29.9 GB/s, integrated graphics Iris Pro Graphics 6200, release date 2015-05-14, launch MSRP $384, part number SR2AL.

Both have 64 KB L1 per core and 256 KB L2 per core, dual-channel memory bus, PCIe Gen 3 with 16 lanes, no ECC memory, no unlocked multiplier, Intel as manufacturer and foundry, and both are end-of-life. The i5-8400T has 6 cores and 6 threads; the i7-5775R has 4 cores and 8 threads. The i5-8400T has a smaller die despite more cores, reflecting the newer architecture. The i7-5775R has a higher TDP by 30 watts, which corresponds to its higher clock speeds.

Head-to-Head Benchmarks

The Cinebench results consistently favor the i7-5775R, but the margins are small. In Cinebench R15 multi-core, the i7-5775R scores 641 versus 633 for the i5-8400T, a 1.2% lead. Single-core R15 sees 90 versus 89, a 1.1% margin. R20 multi-core shows 2671 versus 2638, again 1.2% ahead. R20 single-core is 376 versus 372, 1.1% ahead. R23 multi-core shows 6360 versus 6282, 1.2% ahead, and R23 single-core is 897 versus 886, 1.2% ahead. These are consistent but narrow wins, suggesting the i7-5775R has a slight efficiency edge in Cinebench workloads.

The Geekbench results are where the story diverges. In multi-core, the i5-8400T wins with 4011 versus 3996, a 0.4% advantage. The i7-5775R wins single-core with 1218 against 1100, a 9.7% lead. The single-core gap is the largest in the entire comparison, showing that clock speed matters far outweighs architectural improvements in lightly threaded scenarios.

The i5-8400T's multi-core win in Geekbench is the only case where the i5-8400T beats the i7-5775R. The 4011 score suggests that Geekbench multi-core scales with physical cores more than the Cinebench suite does. That single win balances the overall picture, but it does not overturn the i7-5775R's majority across the other seven tests.

The average scores echo this near-total dominance. The i7-5775R averages 2031 average benchmark score, while the i5-8400T averages 2031 and 2001, meaning it is essentially tied with the i7-5775R on average, within 1% of the i5-8400T in the database's aggregate scoring.

The Verdict

For users prioritizing raw single-thread performance, the i7-5775R is clearly the choice. It wins every single-core benchmark in the comparison, including the notable 9.7% Geekbench single-core lead over the i5-8400T. The i7-5775R also wins all six Cinebench multi-core tests, albeit by only about 1.2% each time. Its higher base clock of 3.30 GHz and boost of 3.80 GHz provide a consistent advantage.

For users running multi-threaded workloads that emphasize physical cores, the i5-8400T has something to offer. Its 6 cores give it a 0.4% winning margin in Geekbench multi-core, the only head-to-head benchmark it claims. The i5-8400T also uses less power at 35 watts versus 65 watts TDP, making it more efficient per watt in at least one key metric. Its DDR4 memory support with 42.7 GB/s bandwidth, double bandwidth of the i7-5775R's DDR3 29.9 GB/s bandwidth, could benefit memory-heavy applications.

The i7-5775R wins 7 of 8 head-to-head benchmarks and leads the i5-8400T in average benchmark score by 1.2% in most Cinebench tests. It ranks at the same 45th percentile as the i5-8400T among all CPUs, making them overall competitive peers. The i7-5775R launched with a launch MSRP of $384, while the i5-8400T launched at $182.

Neither chip has an unlocked multiplier, both are end-of-life, and both target the desktop segment. The i7-5775R uses a BGA 1364 socket, while the i5-8400T uses a socketed LGA 1151, so system compatibility differs drastically. The i7-5775R has been around since 2013, while the i5-8400T is much newer in the database. The data shows it is the i7-5775R that takes the overall advantage across the measured benchmarks, with only a narrow 0.4% i5-8400T win in Geekbench multi-core preventing a clean sweep.