2x8GB Ram sticks rated at 3200 run at 1600

[lervayy]

2x8GB Ram sticks rated at 3200 run at 1600

Does this mean since 2 sticks each run at 1600 = 3200 or is it a problem?

[WereCat]

DDR = Dual Data Rate

1600x2 = 3200

that is the correct speed

[mariushm]

Dual channel means the processor reads from and writes to TWO memory sticks at the same time. This way, the transfer time between memory and CPU is reduced in half. 

 

The memory sticks run at 1600 Mhz. The 3200 Mhz value is marketing, and white lie... it's a way to express the actual performance of a memory stick.

 

In the past we had SDRAM, which made available 1 bit of information on every pin that can transfer information to PC - on a memory stick you have 64 such pins.

So, for every Hz, a memory stick could transfer 64 bits of information.

 

When DDR memory was invented, they made it possible to put 2 bits of information on every pin, but the number of pins remains the same. So, on every Hz of the memory's frequency, the memory stick could now transfer 128 bits of information.

 

First DDR memory sticks used to run at lower frequencies than SDRAM, for example you have 200 Mhz SDRAM and 166 Mhz DDRAM and customers couldn't grasp the concept that even though the frequency was lower, the DDRAM was better because of that 128 bit vs 64 bit transfers on each Hz.

In the example above, you had 200 x 64 vs 166 x 128: the DDR wins.

 

To work around this, the manufacturers simply decided to advertise the DDR memories at double the frequency.

In the example above, the 166 Mhz DDRAM was advertised as 333 Mhz and now the customers saw 200 Mhz and 333 Mhz and thought "of course DDR is better, it's a higher number"

 

DDR2 and DDR3 and DDR4 only make small improvements and jumps in performance, they still transfer only 2 bits of information.

So that's why you have the real frequency of 1600 Mhz and the sticks are sold as 3200 Mhz.

 

GDDR5 memory which is used on video cards puts 4 bits on every pin and that's why you see frequencies like 7000 Mhz - the chips in reality function at 7000/4 = 1750 Mhz.

Also, each tiny memory chip has 32 data pins on it so if you have a video card with 8 memory chips, it's already 256 bit wide, and for every Hz, you get 256 bits x 4 bits per Hz = 1024 bits.... big number, compared to 64 bit x 2 bits per Hz  x 2 (if used in dual channel) = 256 bits per Hz

That's one of the reasons video cards are so fast.

[SupaKomputa]

1 minute ago, mariushm said:

snip

That's a very long answer for a simple question. Nice.

[Princess Luna]

Just now, SupaKomputa said:

That's a very long answer for a simple question. Nice.

Kinda pointless stress about it as well since tomorrow we'll have another thread of the same issue...

 

This is one of those things that will be part of the tech world to the end.

[lervayy]

Th

4 minutes ago, mariushm said:

Dual channel means the processor reads from and writes to TWO memory sticks at the same time. This way, the transfer time between memory and CPU is reduced in half. 

 

The memory sticks run at 1600 Mhz. The 3200 Mhz value is marketing, and white lie... it's a way to express the actual performance of a memory stick.

 

In the past we had SDRAM, which made available 1 bit of information on every pin that can transfer information to PC - on a memory stick you have 64 such pins.

So, for every Hz, a memory stick could transfer 64 bits of information.

 

When DDR memory was invented, they made it possible to put 2 bits of information on every pin, but the number of pins remains the same. So, on every Hz of the memory's frequency, the memory stick could now transfer 128 bits of information.

 

First DDR memory sticks used to run at lower frequencies than SDRAM, for example you have 200 Mhz SDRAM and 166 Mhz DDRAM and customers couldn't grasp the concept that even though the frequency was lower, the DDRAM was better because of that 128 bit vs 64 bit transfers on each Hz.

In the example above, you had 200 x 64 vs 166 x 128: the DDR wins.

 

To work around this, the manufacturers simply decided to advertise the DDR memories at double the frequency.

In the example above, the 166 Mhz DDRAM was advertised as 333 Mhz and now the customers saw 200 Mhz and 333 Mhz and thought "of course DDR is better, it's a higher number"

 

DDR2 and DDR3 and DDR4 only make small improvements and jumps in performance, they still transfer only 2 bits of information.

So that's why you have the real frequency of 1600 Mhz and the sticks are sold as 3200 Mhz.

 

GDDR5 memory which is used on video cards puts 4 bits on every pin and that's why you see frequencies like 7000 Mhz - the chips in reality function at 7000/4 = 1750 Mhz.

Also, each tiny memory chip has 32 data pins on it so if you have a video card with 8 memory chips, it's already 256 bit wide, and for every Hz, you get 256 bits x 4 bits per Hz = 1024 bits.... big number, compared to 64 bit x 2 bits per Hz  x 2 (if used in dual channel) = 256 bits per Hz

That's one of the reasons video cards are so fast.

Thanks for taking the time to explain this to me, appreciate the effort you put into this text, thanks a lot