One of the fundamental components of any computer, be it a bulky desktop or a 6-inch smartphone is the
Now regardless of whether you are an enthusiast or just someone who’s up-to-date with the latest trends in technology, you probably have come across the terms DDR4, GDDR5 (in graphics cards), LPDDR4 (in smartphones) and HBM. People usually get confused between the different memory types and often use GDDR5 and DDR5, interchang
Double Data rate Generation Four (DDR4)
A bit of basic info first. Nearly every kind of memory is based on dynamic random access memory (DRAM).
DDR4 is the latest iteration of DRAM. Released in 2014, it initially didn’t offer significantly faster speeds than it’s predecessor but instead focused on reducing the voltage and power consumption. With the coming of AMD’s Ryzen processors and the Infinity fabric that interconnects the various
DDR4 vs DDR3
Aside from the obvious (faster frequencies and lower latency), the primary advantages of DDR4 memory over DDR3 are higher DIMM sizes (up to 64 GiB, comparatively DDR3 is limited to 16) and lower voltage requirements.
With that out of the way,
DDR3 Vs GDDR5
- DDR3 runs at a much higher voltage than GDDR5, 1.25-1.65 volts to be exact. GDDR5, on the other hand, is usually limited to 1V.
- Both DDR4 and DDR3 use a 64-bit memory controller per channel which results in a 128-bit bus for dual-channel memory and 256 bit for
quad. GDDR5 memory, on the other hand, leverages a puny 32-bit controller per channel.
- However, while CPU memory configurations have wider but fewer channels, GPUs can support any number of 32-bit memory channels. This is the reason many high-end GPUs like the GeForce RTX 2080 Ti and RTX 2080 have a 384-bit and 256-bit bus width, respectively.
Both these cards are connected to 1GB memory chips via 8 (for 2080) and 12 (for the Ti) 32-bit memory controllers or channels. GDDR5/6 can also operate in what is called clamshell mode, where each channel instead of being connected to one memory chip is split between two. This also allows manufacturers to double the memory capacity and makes hybrid memory configurations like the GTX 660 with its 192-bit bus width possible.
- Another core difference between DDR3 and GDDR5/6 memories involves the I/O cycles. Just like
SATAinterface, DDR3 can only perform one operation (read or write) in one cycle. GDDR5 can handle input (read) as well as output (write) on the same cycle, essentially doubling the bus.
- All this might put DDR3/4 memory in a bad light, but this configuration actually suits it. CPUs are heavily sequential when it comes to their workloads and GPUs on the other hand rely on parallel processing. So while CPUs benefits from low latency, GPUs require a much higher bandwidth with loose timings.
High Bandwidth Memory (HBM)
First popularized by AMD Fiji graphics cards, high bandwidth memory or HBM is a low power memory standard with a wide bus. HBM achieves substantially higher bandwidth compared to GDDR5 while drawing much lesser power in a small form factor.
HBM adopts clocks as low as 500 Mhz to conform to a low TDP target and makes up for the loss in bandwidth with a massive bus (usually 4096 bits). AMD’s Radeon RX Vega cards are the best example of HBM2 implementation in consumer hardware. HBM2 solved the 4GB limit of the HBM1, but limited yields coupled with memory shortage prevented AMD from capitalizing on the GPU front.
GDDR5X And GDDR6
GDDR5X is a half-generation upgrade of sorts. It increases the bandwidth of GDDR5 by increasing the base clock and doubling the prefetch (operations per clock). GDDR5X increases the bandwidth to up
As far as GDDR6 is concerned, it increases the memory density to 16Gb while increasing the speed to 16Gbps. GDDR6 is expected to hit a record bandwidth of 16 Gbps while cutting down the voltage by 10% compared to GDDR5. NVIDIA’s Turin and AMD’s Navi graphics cards both leverage GDDR6 memory.
LPDDR4 is the mobile equivalent of DDR4 memory. Compared to DDR4, it offers reduced power consumption but does so at the cost of bandwidth. LPDDR4 has dual 16-bit channels resulting in a 32-bit total bus. In comparison, DDR4 has an 8-word prefetch or a 64-bit channel. Therefore, LPDDR4 RAM halves the bus but makes up for this with a lower operating voltage of 1.1-1.2V.
This allows for greater power efficiency in smartphones and battery standby times of up to 8-10 hours. Micron’s LPDDR4 RAM tops out the standard with a 2133 MHz clock for a transfer rate of 4266 MT/s while Samsung follows shortly after with a clock of 1600MHz and a transfer rate of 3200 MT/s.
So that’s most of what you need to know about RAM or dynamic memory. If you have any doubts or think we missed something, do let us know in the comments section below!
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