Types of memory
1) DRAM / HBM
Role in AI Compute:
- DRAM (Dynamic RAM): Main system memory for CPUs/GPUs/accelerators. Holds working datasets, model parameters, intermediate activations, and general compute state while processing.
- HBM (High-Bandwidth Memory): Specialized DRAM tightly stacked near GPU/accelerator cores. Provides very high throughput at low power compared to DDR DRAM, critical for large matrix multiplications and transformer layers in modern AI.
- In AI contexts, DRAM is about capacity + latency, while HBM is about bandwidth.
Main Suppliers (Public + Tickers):
- Micron Technology — MU (NYSE) — DRAM & HBM supplier via ecosystem partners.
- SK Hynix — 000660.KS (Korea) — DRAM & HBM; one of the largest memory producers globally.
- Samsung Electronics — 005930.KS (Korea) — #1 in DRAM and DRAM-derived products (including HBM).
- Nanya Technology — 2408.TW (Taiwan) — DRAM maker (smaller share).
2) NAND Flash
Role in AI Compute:
- Primary non-volatile storage for SSDs and persistent buffers.
- Used for model storage, weights caching, checkpoints, datasets that don’t fit in RAM and need persistent backing.
- Helps enable fast I/O to feed data into faster DRAM/HBM layers.
Main Suppliers (Public + Tickers):
- Sandisk – SNDK
- Western Digital — WDC (NASDAQ) — NAND flash via joint ventures and SSDs.
- Micron Technology — MU (NYSE) — Major NAND supplier.
- Kioxia (private) — large NAND supplier (not publicly traded as of 2026).
- SK Hynix — 000660.KS (Korea) — NAND products after acquiring Toshiba’s memory business stake.
- Samsung Electronics — 005930.KS (Korea) — Largest NAND flash producer.
3) HDD (Hard Disk Drives)
Role in AI Compute:
- Low-cost, high-capacity bulk storage for datasets, archives, logs, backups.
- Not used for active model training but essential for data lakes, long-term dataset retention, backup copies of models, and cold storage in AI pipelines.
Main Suppliers (Public + Tickers):
- Seagate Technology — STX (NASDAQ) — One of the largest HDD makers for enterprise & cloud.
- Western Digital — WDC (NASDAQ) — Major HDD maker alongside Seagate.
4) SRAM (Static RAM)
Role:
- Ultra-fast memory used on-chip in CPUs/GPUs/accelerators for caches, register files, and local buffers.
- Critical for low-latency access during computation.
Suppliers:
- SRAM is built into chips; there aren’t standalone SRAM producers with significant public tickers. It’s designed inside logic chips by:
- Nvidia — NVDA (NASDAQ)
- AMD — AMD (NASDAQ)
- Intel — INTC (NASDAQ)
- AI ASIC firms (e.g., Google/Alphabet GOOGL, Apple AAPL)
📀 SSD (Solid-State Drive) – NVMe / PCIe Storage
Role:
- Uses NAND flash + controller to provide high-speed persistent storage for datasets and model artifacts.
- Often tiered with DRAM caches to speed I/O for AI training pipelines.
Suppliers:
- SSD controllers and products from:
- Western Digital — WDC (NASDAQ)
- Micron — MU (NYSE)
- Samsung — 005930.KS (Korea)
- Kioxia (private)
- Seagate — STX (NASDAQ)
💾 Emerging / Specialized Memory
These aren’t yet mainstream in AI compute but are relevant in research and low-power AI systems:
| Memory Type | Role | Notes |
|---|---|---|
| MRAM (Magneto-Resistive RAM) | Non-volatile, faster than NAND | Early stage; used in embedded systems |
| ReRAM / PCM | Persistent, low power | Research for in-memory compute |
| Optane (3D XPoint) | Persistent memory between DRAM & NAND | Intel inventor (legacy products) |
Suppliers:
- MRAM & emerging:
- Everspin Technologies — MRAM (MRAM) (NASDAQ)
- Intel — INTC (NASDAQ) (historical with Optane/3D XPoint)
- Samsung / SK Hynix / Micron are researching next-gen memory but not always productized.
Memory Hierarchy Summary (AI Stack)
| Layer | Typical Tech | Role in AI |
|---|---|---|
| On-chip registers & cache | SRAM | Fastest access for computation |
| High-bandwidth pool | HBM | Training/inference compute throughput |
| System memory | DRAM | Working set + dataset buffering |
| Persistent fast storage | SSD (NAND flash) | Model/dataset I/O |
| Bulk/archive storage | HDD | Long-term dataset/backup |
