Quick Verdict
The Iris 6100 graphics made this the most capable dual-core Broadwell-U for GPU workloads, but the 28W TDP limited it to larger ultrabook designs and it remains outdated by modern standards.
Overview
Launch
2015
Status
End-of-lifeGeneration
5th Gen (Broadwell-U)
Market
Mobile
The Intel Core i5-5257U is a 28W dual-core Broadwell-U processor featuring Intel Iris 6100 graphics, targeting premium ultrabooks and MacBook Pro 13-inch models that demanded superior integrated GPU performance.
The Intel Core i5-5257U features 2 cores and 4 threads at 2.7 GHz base and 3.1 GHz turbo, paired with Intel Iris 6100 graphics including 48 Execution Units at 300-1050 MHz.
The 28W TDP allows higher sustained clocks for both CPU and GPU compared to the 15W Broadwell-U variants. It supports DDR3-1866 memory and uses the same 133mm² die as the i5-5250U but with the full GT3 GPU enabled. This processor was designed for premium thin laptops where visual performance mattered, most notably the 2015 MacBook Pro 13-inch with Retina display.
Specifications
Performance
Higher base clock and 28W TDP deliver better sustained performance than 15W variants, but dual-core design still limits multi-threaded workloads.
Slightly better than 15W variants but still fundamentally limited by dual-core design.
Iris 6100 was the best integrated GPU in the Broadwell-U lineup, handling older games at 720p-1080p low settings reasonably well for 2015.
The 28W TDP reduces efficiency compared to 15W variants, requiring active cooling and reducing battery life in thin laptops.
- •Iris 6100 with 48 EUs was the best Broadwell-U GPU option
- •Titles like Dota 2, CS:GO, and League of Legends run at 1080p medium at 30-60 FPS
- •eDRAM cache significantly helps GPU performance
- •Modern games remain unplayable even at lowest settings
- •No AI acceleration hardware
- •GPU compute insufficient for modern AI workloads
- •Not applicable for this processor generation
Architecture
14nm
Process Node
Broadwell-U
Codename
2C / 4T
Core Config
3 MB
L3 Cache
28 W
TDP
Architecture Overview
The i5-5257U uses the full GT3 configuration of the Broadwell-U die. With 48 Execution Units and 128MB of dedicated eDRAM (embedded DRAM) serving as an L4 cache, the Iris 6100 graphics subsystem is fundamentally different from the GT2-class HD 5500 and HD 6000. The eDRAM acts as a high-bandwidth framebuffer for the GPU and a victim cache for the CPU, dramatically reducing memory access latency for graphics workloads and improving CPU performance in cache-sensitive applications. This is the same 133mm² die as the i5-5250U but with the GPU fully enabled rather than partially disabled. The 28W TDP reflects the additional power draw of the full GT3 GPU plus eDRAM, and the configurable TDP down to 23W allows some thermal headroom adjustment for OEMs designing thinner chassis than the traditional 28W thermal solution requires.
CPU Design
Two Broadwell cores with Hyper-Threading, 64KB L1 and 256KB L2 per core, 3MB shared L3 Smart Cache, plus 128MB eDRAM L4 cache accessible by both CPU and GPU.
Memory Subsystem
Dual-channel DDR3-1866 with 29.9 GB/s bandwidth, augmented by 128MB eDRAM providing roughly 48 GB/s bandwidth to the GPU and CPU as L4 cache.
PCIe & I/O
12 PCIe Gen 2 lanes, identical to other Broadwell-U variants.
Overclocking
Locked multiplier, BGA soldered, no overclocking support.
- 14nm process shrink for better efficiency
- Iris 6100 replacing Iris 5100 with more EUs and eDRAM
- Higher turbo boost frequency
- Improved media engine for video encoding/decoding
Key Highlights
- Best integrated GPU in Broadwell-U i5 lineup with Iris 6100
- 128MB eDRAM benefits both CPU and GPU workloads
- 2.7 GHz base clock is strong for a 2015 dual-core
- Good for Retina display driving and 4K output
- Configurable TDP for OEM flexibility
- 28W TDP limits use to larger ultrabook designs
- Only 2 physical cores with dual-core limitation
- DDR3 memory is obsolete
- Active cooling required in all implementations
- End-of-life with no security updates
- Not Windows 11 compatible
History
The Core i5-5257U emerged as the heart of Apple's 2015 MacBook Pro 13-inch Retina, making it one of the most recognizable Broadwell-U processors. Intel created the 28W U-series tier specifically for premium ultrabooks and Apple's professional laptop line, where the 15W TDP would have sacrificed too much GPU performance for the Retina display.</br></br>The inclusion of Iris 6100 with 48 Execution Units and 128MB of eDRAM was significant.
Intel had been developing eDRAM technology for its high-end server products, and bringing it to consumer mobile chips represented a substantial investment. The eDRAM served dual purposes: accelerating GPU workloads by providing a dedicated high-bandwidth framebuffer and acting as an L4 victim cache that boosted CPU performance in memory-sensitive applications.</br></br>However, the 28W TDP placed this chip in an awkward middle ground.
It was too power-hungry for the thinnest ultrabooks but lacked the performance of true 45W+ mobile workstation processors. As Apple and other OEMs moved toward higher-resolution displays and more demanding creative applications, the dual-core limitation became increasingly apparent. The i5-5257U would be one of the last dual-core processors used in Apple's professional laptop line before quad-core became the standard.
Improvements over Previous Generation
- 14nm process shrink for better efficiency
- Iris 6100 replacing Iris 5100 with more EUs and eDRAM
- Higher turbo boost frequency
- Improved media engine for video encoding/decoding
Alternatives & Competitors
Should You Buy It?
Not Recommended for the right buyer
Buying a used MacBook Pro 13-inch 2015 for under $150 for basic use with a Retina display
Avoid if…
- Purchasing a new laptop in 2026
- Any gaming beyond casual browser games
- Video editing at resolutions above 1080p
- Running Windows 11
- Needing modern security features like TPM 2.0
Use Cases
Interesting Facts
The i5-5257U was the base processor in the 2015 MacBook Pro 13-inch Retina, one of the most popular premium laptops of its era.
Iris 6100 includes 128MB of eDRAM (embedded DRAM) on the processor package, acting as an L4 cache — a feature not present in HD 5500/HD 6000 variants.
The eDRAM provides approximately 48 GB/s bandwidth, nearly double the DDR3-1866 system memory bandwidth.
With 48 Execution Units, Iris 6100 has exactly double the EUs of HD 5500/HD 6000.
This processor was part of the last generation of Intel-powered MacBook Pros before the Touch Bar redesign in 2016.
The 28W TDP class was specifically created for premium ultrabooks that needed more GPU performance than 15W allowed.
Iris 6100 was the first Intel integrated GPU that could reasonably handle 4K video output at 60Hz.
The eDRAM cache was a technology Intel initially developed for server products but brought to consumer chips specifically for graphics performance.
At $315, the i5-5257U was priced the same as the i5-5250U and i5-5287U despite offering a different TDP and GPU tier.
The configurable TDP down to 23W was unique to the 28W Iris models, giving OEMs a middle ground option.
People Also Ask
What is the difference between i5-5257U and i5-5250U?
The i5-5257U has a 28W TDP (vs 15W), Iris 6100 graphics with 48 EUs (vs HD 6000 with 24 EUs), 128MB eDRAM (vs none), higher base clock (2.7 vs 1.6 GHz), and higher turbo (3.1 vs 2.7 GHz).
What Mac used the i5-5257U?
The 2015 MacBook Pro 13-inch with Retina display used the i5-5257U as its standard processor.
Is the i5-5257U good for gaming?
For 2015 standards, the Iris 6100 was decent for casual gaming. In 2026, it can only handle very old or lightweight titles at low settings.
Does the i5-5257U have eDRAM?
Yes, it includes 128MB of eDRAM on the processor package, which acts as an L4 cache for both CPU and GPU workloads.
Can the i5-5257U run Windows 11?
No, it does not meet Windows 11's TPM 2.0 and supported CPU requirements.
What is the TDP of the i5-5257U?
The standard TDP is 28W with a configurable TDP down to 23W.
How does Iris 6100 compare to HD 5500?
Iris 6100 with 48 EUs and 128MB eDRAM is roughly 60-80% faster than HD 5500 with 24 EUs and no eDRAM, depending on the workload.
Is the i5-5257U still usable in 2026?
Barely. It handles basic web browsing and document editing but struggles with modern web applications, multitasking, and any GPU-intensive workload.
Why does the i5-5257U need 28W instead of 15W?
The full GT3 GPU with 48 EUs and 128MB eDRAM draws significantly more power than the GT2 GPU in 15W variants, requiring the higher TDP budget.
Does the i5-5257U support 4K displays?
Yes, Iris 6100 can drive 4K displays at 60Hz via DisplayPort and at 30Hz via HDMI, though performance at 4K resolution is limited.
Frequently Asked Questions
How much eDRAM does the i5-5257U have?
It has 128MB of eDRAM (embedded DRAM) on the processor package.
What is the graphics clock range for Iris 6100?
The Intel Iris 6100 graphics clock ranges from 300 MHz to 1050 MHz.
Can I upgrade from the i5-5257U?
No, the BGA 1168 socket means the processor is permanently soldered to the motherboard.
Does the i5-5257U support hardware video encoding?
Yes, it supports Intel Quick Sync Video for hardware-accelerated H.264 encoding and decoding.
What is the maximum turbo frequency of the i5-5257U?
The maximum Intel Turbo Boost 2.0 frequency is 3.1 GHz.
Does the eDRAM help CPU performance?
Yes, the 128MB eDRAM acts as an L4 victim cache for the CPU as well as a GPU framebuffer, improving performance in cache-sensitive workloads by 5-15%.
What is the part number of the i5-5257U?
The standard part number is SR26K.
Is the i5-5257U good for programming?
It handles basic IDE work and text editing but compilation and running multiple services will be slow due to the dual-core limitation.
Does the i5-5257U support Thunderbolt?
Thunderbolt 2 support depends on the laptop's motherboard implementation, not the CPU directly. Many laptops with this chip did include Thunderbolt 2.
What memory does the i5-5257U support?
It supports dual-channel DDR3-1866 memory up to 16GB.