Core i3-8121U vs Core i5-2550K

PassMark CPU Mark evaluates processor speed through complex mathematical computations. It provides a reliable metric to compare multi-core performance, where higher scores indicate faster processing for multitasking, gaming, and heavy workloads.

Core i3-8121U vs Core i5-2550K FPS Benchmarks

Predicted gaming performance across popular games. Tested paired with GeForce RTX 5090 to isolate CPU performance.

Search any supported game below to compare 1080p FPS for both components.

Core i3-8121U vs Core i5-2550K: Pros, Cons & Final Verdict

See where each CPU makes more sense in practice: gaming, heavier work, platform cost, power draw, and upgrade path.

Core i3-8121U

2018

Why buy it

✅+66.6% higher Geekbench single-core performance for gaming and desktop responsiveness.
✅Draws 15W instead of 95W, a 80W reduction.

Trade-offs

❌Smaller total L3 cache (4 MB vs 6 MB).
❌No boxed cooler included, unlike Core i5-2550K.

Core i5-2550K

2012

Why buy it

✅+50% larger total L3 cache (6 MB vs 4 MB).
✅Includes a boxed cooler (Yes), unlike Core i3-8121U.

Trade-offs

❌Lower Geekbench single-core performance for gaming (707 vs 1,178).
❌Lower Geekbench multi-core (2,010 vs 2,250).
❌Launch MSRP is still $235 MSRP, while Core i3-8121U mostly shows up through inconsistent older-market listings.
❌533.3% higher power demand at 95W vs 15W.

Quick Answers

So, is Core i3-8121U better than Core i5-2550K?

Yes. Core i3-8121U is the better all-around CPU here. It gives you a 1.2% average FPS lead across 50 shared CPU game tests in our data, 11.9% better Geekbench multi-core, 1.0% higher PassMark, and the stronger long-term platform, which is enough to make it the stronger overall pick.

Which one is better for gaming?

If gaming is the priority, Core i3-8121U is the better pick. According to our tests, it delivers 1.2% more average FPS across 50 shared CPU game tests.

Which one is better for streaming, content creation, and heavy multitasking?

For streaming, content creation, and heavier multitasking, Core i3-8121U is the stronger fit. You are getting 11.9% better Geekbench multi-core, backed by 2 cores and 4 threads.

Which one is the smarter buy today, not just the cheaper CPU?

Core i3-8121U is still the much better call for a fresh build. Core i3-8121U comes in at an unclear MSRP at unclear MSRP versus $235 MSRP, and it still gives you a 1.2% average FPS lead across 50 shared CPU game tests in our data. Core i5-2550K only looks stronger on raw value math because it is extremely cheap, but that usually means used-market pricing on an obsolete 2012 platform. Even with 100.0% better value on paper (18.0 vs 0.0 PassMark/$), it really only makes sense as a cheap stopgap or a niche existing-platform option for someone already on LGA1155.

Which one is more future-proof for 2026 and beyond?

Core i3-8121U makes more sense long term for 2026 and beyond. You are getting a newer CPU generation (2018 vs 2012) and more multi-core headroom with 2 cores / 4 threads instead of 4/4. That extra compute headroom is more likely to matter as games, background tasks, and creator workloads get heavier.

Core i3-8121U vs Core i5-2550K Technical Specifications

Side-by-side specs, architecture details, clocks, memory, power, and platform differences.

Core i3-8121U

The Core i3-8121U is manufactured by Intel. It was released in 5 May 2018 (7 years ago). It is based on the Coffee Lake-U (2018−2019) architecture. It features 2 cores and 4 threads. Base frequency is 2.2 GHz, with boost up to 3.2 GHz. L3 cache: 4 MB (total). L2 cache: 256K (per core). Built on 10 nm process technology. Socket: BGA1440. Thermal design power (TDP): 15 Watt. Memory support: DDR4. Passmark benchmark score: 4,271 points. Launch price was $69.

Core i5-2550K

The Core i5-2550K is manufactured by Intel. It was released in Janeiro 2012 (13 years ago). It is based on the Sandy Bridge (2011−2013) architecture. It features 4 cores and 4 threads. Base frequency is 3.4 GHz, with boost up to 3.8 GHz. L3 cache: 6144 kB (total). L2 cache: 256 kB (per core). Built on 32 nm process technology. Socket: LGA1155. Thermal design power (TDP): 95 Watt. Memory support: DDR3. Passmark benchmark score: 4,228 points. Launch price was $189.

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Processing Power

The Core i3-8121U packs 2 cores / 4 threads, while the Core i5-2550K offers 4 cores / 4 threads — the Core i5-2550K has 2 more cores. Boost clocks reach 3.2 GHz on the Core i3-8121U versus 3.8 GHz on the Core i5-2550K — a 17.1% clock advantage for the Core i5-2550K (base: 2.2 GHz vs 3.4 GHz). The Core i3-8121U uses the Coffee Lake-U (2018−2019) architecture (10 nm), while the Core i5-2550K uses Sandy Bridge (2011−2013) (32 nm). In PassMark, the Core i3-8121U scores 4,271 against the Core i5-2550K's 4,228 — a 1% lead for the Core i3-8121U. Geekbench 6 single-core — the metric most relevant to gaming — records 1,178 vs 707, a 50% lead for the Core i3-8121U that directly translates to higher frame rates. Multi-core Geekbench: 2,250 vs 2,010 (11.3% advantage for the Core i3-8121U). L3 cache: 4 MB (total) on the Core i3-8121U vs 6144 kB (total) on the Core i5-2550K.

Feature	Core i3-8121U	Core i5-2550K
Cores / Threads	2 / 4	4 / 4+100%
Boost Clock	3.2 GHz	3.8 GHz+19%
Base Clock	2.2 GHz	3.4 GHz+55%
L3 Cache	4 MB (total)	6144 kB (total)+50%
L2 Cache	256K (per core)	256 kB (per core)
Process	10 nm-69%	32 nm
Architecture	Coffee Lake-U (2018−2019)	Sandy Bridge (2011−2013)
PassMark	4,271+1%	4,228
Cinebench R23 Multi	—	4,058
Geekbench 6 Single	1,178+67%	707
Geekbench 6 Multi	2,250+12%	2,010

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Memory & Platform

The Core i3-8121U uses the BGA1440 socket (PCIe 3.0), while the Core i5-2550K uses LGA1155 (PCIe 2.0) — making them incompatible on the same motherboard. Maximum memory speed reaches DDR4-2400 on the Core i3-8121U versus DDR3-1600 on the Core i5-2550K — the Core i3-8121U supports 50% faster memory, which can translate to measurable gains in memory-sensitive workloads. Both support up to 32 GB of RAM. Both feature 2-channel memory with ECC support. Both provide 16 PCIe lanes. Chipset compatibility: SoC (Core i3-8121U) and Z77,Z75,Q77,H77,Q75,B75,Z68,P67,H67,Q67,B65,H61 (Core i5-2550K).

Feature	Core i3-8121U	Core i5-2550K
Socket	BGA1440	LGA1155
PCIe Generation	PCIe 3.0+50%	PCIe 2.0
Max RAM Speed	DDR4-2400+50%	DDR3-1600
Max RAM Capacity	32 GB	32 GB
RAM Channels	2	2
ECC Support	No	No
PCIe Lanes	16	16

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Advanced Features

Only the Core i3-8121U supports AVX-512 instructions — important for machine learning and scientific applications. Virtualization support: VT-x, VT-d, EPT (Core i3-8121U) vs Yes (Core i5-2550K). Primary use case: Core i3-8121U targets Productivity. Direct competitor: Core i3-8121U rivals Core i3-8130U.