GDDR5 has had a good run. The first graphics cards with GDDR5 memory debuted way back in June 2009, with AMD’s HD 4870. Seven years is a long time for a memory standard, especially in graphics. GDDR4 launched with the X1950 XTX in October 2006, and GDDR3 came out in early 2004 (GeForce 5950 PCIe). In 2015, AMD’s Fury X was the first card in years to use something different: HBM, or High Bandwidth Memory. If you’re wondering why GDDR5 has stuck around and what’s taking HBM so long to show up again, don’t worry—there are new things on the horizon for 2017.
Both Nvidia and AMD should have some new technology on the way in their next graphics cards. Here’s what you need to know.
Right now: GDDR5X and HBM
We can already trace two different paths forward for VRAM in shipping hardware: HBM and GDDR5X. HBM was first used in AMD’s R9 Fury X, along with the Fury and Nano—and it remains the one and only GPU that utilized the standard. Featuring a clockspeed of 500MHz, double-data-rate technology, and a massive 4096-bit interface, each pin can transmit up to 1Gbps, or 512GB/s in total. The big drawback with HBM (aka HBM1) is that each package was limited to 1GB of capacity, meaning 4GB total.
GDDR5X, as you might guess from the name, is similar to GDDR5. Technically, GDDR5X can run in one of two modes, double-data-rate or quad-data-rate. In practice, most implementations have used the QDR variant, which trades slightly lower base clocks for higher overall bandwidth. Where HBM goes for a very wide interface and clocks it relatively slow, GDDR5X opts for a narrower (but still wide) interface that’s clocked much higher—10-14Gbps per pin is typical. With 10Gbps and a 256-bit interface like the GTX 1080, that yields 320GB/s, while the 1080 Ti uses a 352-bit and 11Gbps for 484GB/s.
The two next generation VRAM types build on HBM and GDDR5X: HBM2…