RAM (Random Access Memory) is the CPU’s high-speed workbench. Programs load their working data into RAM so the CPU can read/write it quickly. With enough capacity and speed, apps launch faster and multitasking stays smooth.
Photo by Athena Sandrini on Pexels
As DDR generations evolved from DDR1 → DDR5, transfer rates, bandwidth, and power efficiency improved. Before you buy, double-check your motherboard support, capacity needs, dual-channel setup, clock & timings, and brand/QVL.
What RAM Does (and Why It Matters)
When you launch an app, files on your SSD/HDD are copied into RAM, and the CPU works on that data from there. If the CPU is the brain, RAM is short-term memory — fast, temporary, and cleared when power is off.
Capacity = desk size. A bigger desk lets you keep more “open books” (apps/tabs) at once.
Too little RAM → the system borrows swap/virtual memory on the SSD/HDD (much slower) → stutter and freezes.
Enough RAM → smooth multitasking (many browser tabs + music + photo editor), fewer forced tab reloads, less in-game hitching.
RAM also buffers between a fast CPU and a slower SSD, keeping the CPU busy instead of waiting on storage.
DRAM → SDRAM → DDR: a quick history
DRAM stores data as electric charge and must be refreshed periodically (“Dynamic”).
SDRAM synchronized RAM that moves in step with the CPU clock → more stable and faster I/O.
DDR SDRAM transfers data on both clock edges (Double Data Rate). Today’s modules are DDR4/DDR5 SDRAM.
Generation gains: higher clocks, wider bandwidth, lower voltage, smarter power delivery.
DDR4 vs DDR5 (at a glance)
| Feature | DDR4 | DDR5 |
|---|---|---|
| Typical voltage | ~1.2 V | ~1.1 V (with on-DIMM PMIC) |
| Base speeds (JEDEC) | ~2133–3200 MT/s | 4800 MT/s and up (8000+ MT/s common on OC kits) |
| Bandwidth per DIMM | Lower | Higher (per-DIMM bandwidth scales more) |
| Power management | On motherboard | On-module PMIC → steadier power delivery |
| Latency (general) | Often lower at like-for-like clocks | Raw clocks are higher; effective latency varies by kit |
| Compatibility | Boards with DDR4 slots only | Boards with DDR5 slots only |
⚠️ Slots differ. You cannot insert DDR5 into a DDR4 board (and vice versa). Always verify your board’s supported generation.
How Much RAM Do You Need?
Office / web / media: 8–16 GB
Gaming (1080p/1440p): 16 GB (heavy titles or lots of mods: 32 GB)
Photo/video editing / streaming / music production: 32 GB+
AI / heavy data / VMs: 32–64 GB (or more, as needed)
Balance is key: too little hurts performance; too much beyond your workload brings little real-world gain.
Speed, Timings, and Channels
Clock / Data Rate (MT/s): Higher = more bandwidth. Helps games that stream lots of assets, and creator/AI workloads.
Timings (e.g., CL36): Lower is better (less waiting per access). Compare at similar data rates.
Dual Channel: Install two matched DIMMs to double memory bandwidth vs single-channel.
XMP (Intel) / EXPO (AMD): One-click profiles that set rated speed/timings in BIOS/UEFI.
QVL (Qualified Vendor List): Check your motherboard’s RAM compatibility list for proven kits.
Brands and Modules
IC makers: Samsung, SK hynix, Micron (chips used across many brands).
Module brands: G.Skill, Corsair, Kingston/HyperX, Crucial, TeamGroup, etc.
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General guidance:
Prioritize stability/compatibility → mainstream kits from reputable brands; check QVL.
For gaming/OC → consider higher-speed kits (e.g., G.Skill Trident Z, Corsair Dominator).
RGB is aesthetics only — nice for builds, irrelevant to performance.
Pre-Purchase Checklist
Generation: Is your board DDR4 or DDR5? (They are not cross-compatible.)
Capacity: Match to your workload (see guide above).
Dual Channel: Prefer a 2-DIMM kit (e.g., 2×8 GB, 2×16 GB) rather than a single stick.
Speed & Timings: Balance higher MT/s with reasonable CL. Enable XMP/EXPO after install.
QVL Compatibility: Check your board maker’s list for the exact kit model.
Heatsink Height: Ensure tall heatspreaders won’t collide with your CPU cooler.
Brand/Warranty: Choose reputable brands with solid support and clear warranty terms.
Wrapping Up
RAM isn’t a storage box — it’s the workspace that lets your CPU fly. Pick the right capacity and a sensible speed/timing for your workload, install in dual channel, and enable XMP/EXPO. You’ll feel the difference in responsiveness, load times, and overall workflow.
Next up: Storage (SSD/HDD) — speed, endurance, interfaces, and what actually matters when you’re buying.
You can view the original Korean blog post at the link below