1333 MHz at half the speed?

[DigitalFlower]

Hi! everyone, i'm new here, i have been looking for a while about this, and well, i've found something interesting that i'm sure most of you already knew, that RAM runs at half the speed it's labeled!! i have this corsair  modules and they say in their specs that it was tested at 1333 MHz, does that mean that the actual clock was 1333 MHz or is it the same as with labelling, that they say 1333 and it's really 666.7 what they tested it with? i'm asking because i tried to manually select the clock on my motherboard's BIOS but there was a memory error so it would not post, so i had to reset bios with the button, and had it set to auto again, any ideas on how to get those modules to run at REAL 1333 MHz?  thank you!!

[Virtual01]

They are running at 1333. DDR stands for Double Data Rate and basically your RAM runs at half the advertised speed, but delivers two pieces if information per cycle, making for an effective speed of 1333MHz.

[DigitalFlower]

oooh, that is very interesting, i didn't know that, and here i was sitting thinking how i could get it running faster.

 

thank you!

[vanished]

yeah don't try to run it at actual 1333, it will be at 2666 and probably won't work without some serious voltage hikes

[DigitalFlower]

oh, trust me, i won't, bad enough experience with my pc not posting!!

 

thank you!

[SteveGrabowski0]

RAM is really listed in MT/s (mega transfers per second) instead of clockspeed (Mega Hertz = Mega cycles per second). DDR RAM can do one transfer on the rising edge of a clock and one on the falling edge, allowing it to two transfers per clock cycle. So the effective speed of your RAM would be

 

clockspeed * transfers per clock cycle = (666.5 MHz) * (2 Transfer / Cycle) = (666.5 Mega Cycle / Second) * (2 Transfer / Cycle) = 1333 Mega Transfer / Second = 1333 MT/s