Hacker News Reader

That's 250 GigaBit/s, this is 320 GigaByte/s. No?

From the GDDR5 Wikipedia entry (http://en.wikipedia.org/wiki/GDDR5):

The newly developed GDDR5 is the fastest and highest density graphics memory available in the market. It operates at 7 GHz effective clock-speed and processes up to 28 GB/s with a 32-bit I/O.[4] 2 Gbit GDDR5 memory chips will enable graphics cards with 2 GiB or more of onboard memory with 224 GB/s or higher peak bandwidth.

So, no, it seems that's bytes.

Wow. That does seem to require a crazy 512-bit wide bus though. The info I can find on HMC seems like it is achieving these speeds on a 16-bit bus and with much lower power requirements than even DDR3 so far.

Ok now that's new to me. If you can go 320GB/s on a measly 16bit bus, then it's really feasible to have this as your main memory. On the other hand imagine what you can do with this memory on a GPU, you'd probably get over 1TB/s there. Actually, that's something NVIDIA already has on their roadmap as far as I remember seeing it at GTC.

In the spec they talk about 8-links each is 16 bit(or lanes in their jargon) , which comes out to 128 bit (or 256 bit - there are some configurations where input and output bits are on different pins).

It's gigabytes, not gigabits.

Reply on news.ycombinator.com