DDR3 RAM is 667MHz but it should be 1600MHz?

[temple_treefrog]

Hi all,

I recently upgraded to a ASUS P755D PRO motherboard which supports RAM speeds up to 2133MHz and a G.Skill Trident DDR3 4GB kit.

For some reason (according to CPU-Z) my DRAM frequency stays at 668MHz. How can I change this to 1600MHz or higher?

I expected it would just operate at 1600MHz out of the box.

[phurtive]

Multiply that number by 2 and THAT is your actual MHz. :)

For example, my CPU-Z says my memory is 780MHz, which means it's running at 780MHz x2 = 1560 MHz

I forget exactly why it is this way, but it's just how DDR3 is. It's doubled.

Edit: Ok, after a quick Google I remember. DDR memory is double pumped, so I was right, it's double of what the MHz says.

To change your MHz, go in the BIOS and change the FSB:DRAM ratio. It might be set on "auto" but you can change the ratio to something like 1:2, 1:3, 1:3.3333, 1:4, etc., whichever speed fits your memory's specs best is ideal, but keep in mind that overclocking memory can lead to even more advanced tweakings needing to be done, including DRAM Voltage.

[Pam14160]

Check the packaging that came with your ram to see if it indicates it is 1600 MHz. If so try another program to see if you are getting the proper clock speed. Belarc is a good one.

[DrScouse]

DDR = DOUBE DATA RATE :D

Was in the middle of posting before phurtive revelaed answer!!!

We have no idea if OP is overclocking, would be good to start with a clean slate, everything at stock/default to see what settings should be, then start tweaking in stages as desired... Would agree the divider seems off though..

[temple_treefrog]

Ahh thanks guys, I didn't realise I had to double the MHz value.

I've found a program called ASUS TurboV which helps OC so I will use that.

Thanks :)

[phurtive]

Ahh thanks guys, I didn't realise I had to double the MHz value.

I've found a program called ASUS TurboV which helps OC so I will use that.

Thanks :)

My pleasure, just be careful not to accidentally FRY anything! ;)

[Jason S. Global Moderator]

Multiply that number by 2 and THAT is your actual MHz. :)

For example, my CPU-Z says my memory is 780MHz, which means it's running at 780MHz x2 = 1560 MHz

I forget exactly why it is this way, but it's just how DDR3 is. It's doubled.

Edit: Ok, after a quick Google I remember. DDR memory is double pumped, so I was right, it's double of what the MHz says.

hehe youre almost there... lets clear this up.

Multiply that number by 2 and THAT is your theoretical MHz. Your actual MHz is what is displayed in CPU-Z.

DDR = double data rate. two bits can be "sent" on each clock cycle, hence the name. this is why the companies sell it as 1600MHz memory.

[temple_treefrog]

hehe youre almost there... lets clear this up.

Multiply that number by 2 and THAT is your theoretical MHz. Your actual MHz is what is displayed in CPU-Z.

DDR = double data rate. two bits can be "sent" on each clock cycle, hence the name. this is why the companies sell it as 1600MHz memory.

Hey Jdawg, I noticed that your running an ASUS P6T series motherboard. How did you get your RAM running @ 1600MHz? Did you use the ASUS TurboV software?

Also, does increased DRAM frequency improve the speed/responsiveness of Windows and day-to-day desktop applications?

[Ci7]

it is actually 668Mhz ram , effective speed 1333mhz (what you well see in the bios)

P55 chipset doesn't officially support speed higher then 1333mhz

what you can do is bump memory multiplier a until it become at the rated speed => 1600mhz

and dont forgot to change the ram voltage to the one rated for your rams, in your case change it from the defualt value 1.5v to 1.6v

on the other note

i hope DIMM manufacturer shift high performance ram to 1.5v standard sooner then later ,rather bothersome having to bump voltage

[temple_treefrog]

it is actually 668Mhz ram , effective speed 1333mhz (what you well see in the bios)

P55 chipset doesn't officially support speed higher then 1333mhz

what you can do is bump memory multiplier a until it become at the rated speed => 1600mhz

and dont forgot to change the ram voltage to the one rated for your rams, in your case change it from the defualt value 1.5v to 1.6v

on the other note

i hope DIMM manufacturer shift high performance ram to 1.5v standard sooner then later ,rather bothersome having to bump voltage

Thanks for that Ci7! :)

Silly question, why does the RAM voltage need to be increased? Can ASUS TurboV software do this automatically? :blink: