This article covers Crucial RAM 8GB キット (2x4GB) DDR4 2666MHz CL19 ノートパソコンメモリ CT2K4G4SFS6266.

Overview

The Crucial CT2K4G4SFS6266 is an 8GB DDR4 SO-DIMM memory kit consisting of two 4GB modules. Operating at 2666MHz with CL19 latency, it delivers standard JEDEC performance suitable for everyday notebook computing. Manufactured under Micron's rigorous quality control, this kit leverages over 42 years of memory engineering experience. It runs at a low 1.2V voltage, keeping heat output minimal while ensuring stable operation. With a PC4-21300 rating and 260-pin SO-DIMM form factor, this memory is drop-in compatible with the vast majority of DDR4-equipped laptops released since 2015.

Compatibility Guide

Memory Standard: DDR4-2666 (PC4-21300) Form Factor: 260-pin SO-DIMM Voltage: 1.2V (standard JEDEC) Rank Configuration: 1Rx16 (single rank) This kit works with Intel Core processors 6th-gen (Skylake) and newer, as well as AMD Ryzen 2000 series APUs and later. Crucial's System Scanner tool lets you verify compatibility with your specific laptop model before purchase.

Product Info

Available since around 2020, this memory kit is widely stocked on and other retailers. Its price hovers around ¥2,000–3,000, making it one of the most affordable DDR4 SO-DIMM options on the market. Capacity: 8GB (2x 4GB) Speed: DDR4-2666 (PC4-21300) Latency: CL19 ECC: Non-ECC Positioned as an entry-level upgrade, it's ideal for basic office work, web browsing, and extending the life of older laptops running on limited RAM.

Best Use Cases

1. Light Office and Web Users If your current laptop struggles with Windows 11 or stutters with multiple browser tabs, 8GB is a meaningful upgrade. Why it fits: Low cost, immediate improvement in multitasking Not for: Video editors or 3D gamers who need 16GB+ ### 2. Secondary or Family Laptops For a spare machine used for schoolwork or media consumption, 8GB is often plenty. Why it fits: Low power draw keeps thermals in check on thin laptops Not for: Heavy virtualization or large dataset work ### 3. Budget-Conscious DIY Upgraders When memory prices spike, this kit remains consistently affordable and readily available. Why it fits: Direct Micron quality without the premium Not for: Those seeking high-speed memory (3200MHz+) for gaming ## Alternatives

ADATA Premier DDR4 2666: Similar price and specs, but uses unknown NAND sources; Crucial offers better long-term reliability. ADATA also lacks a compatibility scanner tool. Kingston ValueRAM KCP426S8/4: Often sold as single modules; buying two separately may cost more than this kit. Kingston's warranty is comparable, but the Crucial kit provides a matched pair out of the box. For most users, the Crucial kit is the safer choice thanks to its Micron heritage and built-in compatibility checker.

Things to Consider

Before purchasing, confirm your laptop has free SO-DIMM slots – some ultrabooks have soldered memory with no upgrade path. While rated for 2666MHz, the actual speed depends on your motherboard's maximum supported DDR4 speed. Older systems may run it at 2133 or 2400 MHz, but the kit will downclock automatically without issues. 8GB is insufficient for modern AAA gaming, 4K video editing, or heavy productivity. If you plan to do any of those, look for a 16GB or 32GB kit. This is a dual-module kit; ensure you install both in the correct slots for dual-channel operation. Some older laptops only support single-channel, which halves memory bandwidth. ## FAQ Q: Can I use this memory in a DDR3 laptop? A: No. DDR4 operates at 260 pins vs DDR3's 204 pins, and the notch position is different. They are physically incompatible. Q: Can I use just one 4GB module from this kit? A: Yes. Each module is a standard 4GB DDR4 stick and will work alone, though you will lose dual-channel performance. Q: Is this kit compatible with Lenovo ThinkPad X280? A: Yes, the X280 uses DDR4 SO-DIMM. Crucial's compatibility list confirms it, and the system has one free slot to upgrade from 4GB to 8GB.

Product Disclosure (Amazon)

  • Manufacturer: Crucial(クルーシャル)
  • Seller: R・STORE【適格請求書発行事業者】
  • Fulfilled by: R・STORE【適格請求書発行事業者】
  • ASIN: B07NZ8C7FW
  • Note: This article covers a manufacturer-made product based on Amazon listing details.