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DDR3 Ram clock speed is lower than expected, Why?

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June 6, 2012 9:35:37 AM

Hello, I'm a newbie in pc hardware. My system is operating in DDR3 800Mhz. in my bios settings , DRAM Frequency is set to Auto by default and when system boots , it says operating in DDR3 800,But I expect higher,eg 1066 or 1333. when i change DRAM frq to eg 1066 or 1333 system wont boot untill i clear CMOS. am i going to get 1066 or 1333 anyway?

my mainboard is EliteGroup P43T-AD3 :
Socket : LGA775
Chiposets : P43 (NB) - ICH10(SB)
Maximum System FSB Supported: 1333
Memory Support : DDR3 1600/1333 (OC)/1066/800 DDR3 SDRAM with Dualchannel architecture
Bios : AMI
=============
My CPU : Intel Pentium E5400 Dual Core , 2.7Ghz ,Rated FSB : 800 Mhz , Bus Speed : 200 Mhz , Core Speed : 1200 Mhz , Multiplier : x6

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My RAM : Apacer DDR3-1333 (PC-10700-667MHZ) 2GB x2 ==> 4GB Toatally Channels # : Dual
DC Mode : Symmetric
Dram Frequency : 400 Mhz
FSB : DRAM = 1:2

Sorry 4 bad English
Thank You
a b V Motherboard
June 6, 2012 9:46:55 AM

E5400 only support up to 800 Mhz, doesn't seems increase it to 1066 will give u much benefit since your cpu bounded.
a c 431 V Motherboard
June 6, 2012 9:47:25 AM

Hey mike welcome to the forum. first off use cpu-z and look under the spd info for your ram. the last line on the right will tell you the max speed the ram can run and the voltage and timing it needs to be set at. with most ram that last line on intel motherboards are called the xmp profile. if your motherboard is set to that then i would leave it alone. with some motherboard they show the bus speed of the ram. some motherboard show the clock speed of the ram. your motherboard show the bus speed. with ddr2 and faster ram you have to go 2x the bus speed to show what the ram in running. as most ddr2 and ddr3 can do two things per clock cycle. so bus speed of 533=1066 bus of 667 is 1333 and bus of 800 is 1600.
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June 6, 2012 10:06:19 AM

@rdc85 , @smorizio first of all : thank u

@smorizio
it seems that i cant understand exactly what u mean ( i'm a newbie :)  )

but here is My SPD section of CPU-Z hope it helps:

Module Size : 2048 MB
Max Bandwith : PC3-10700 (667 MHz)


and i think JEDEC# 4 is wanted :
JEDEC# 4 :
Frequency : 685 MHz
CAS# Latency : 9.0
RAS# to CAS# : 9
RAS# Precharge : 9
tRAS : 25
tRC : 34
Voltage : 1.50
a c 431 V Motherboard
June 6, 2012 10:32:53 AM

why it locking up is the ram is already runing faster then it rated for. the bus speed is 400. in the bios. at the dram speed is set 1:2...that would be the dram speed is 800. in your mb you have to have buss speed of 333@2 to get 667. so right now your running the ran a little faster then it rated for. as it stable on auto i would leave it alone.
June 6, 2012 10:40:32 AM

what happens if I change my CPU with a FSB 1333 one?
a b V Motherboard
June 6, 2012 11:52:45 AM

It's not clocked lower than expected, it's overclocked. You have 667mhz ram....your running it at 800mhz....

It doesn't matter what cpu you use, your already overclocking the ram past it's rated speed.

If I were you I would clock it back down to 667 before it fails and you have to buy new ram.

333x2 (ddr) = 667mhz. Right now your running 400x2 (ddr) = 800mhz
June 7, 2012 10:14:50 AM

geekapproved said:
It's not clocked lower than expected, it's overclocked. You have 667mhz ram....your running it at 800mhz....

It doesn't matter what cpu you use, your already overclocking the ram past it's rated speed.

If I were you I would clock it back down to 667 before it fails and you have to buy new ram.

333x2 (ddr) = 667mhz. Right now your running 400x2 (ddr) = 800mhz



package of my ram says : DDR3-1333 . what it means? i think it says 1333 so it most be detected 1333 by post.
well , i didnt over clock anything. DRAM Freqeuncy in bios is set to Auto.
am i going to lower clock my ram with Dram Frequency?
a c 431 V Motherboard
June 7, 2012 6:35:11 PM

right now your ram is running faster then it rated for. it running at 1600 speed (800*2) it should be running at 667.
September 13, 2012 7:41:26 PM

Hi all,
Are you all sure he is running it faster than rated? Didn't seem that way to me. I.e., are you sure it's correct where you calculate he is running at 800*2 = 1600...?
I.e., I'm unsure how you got a bus speed of 400Mhz? In OP's original post didn't he say bus speed is 200 (and rated fsb is 800).
I thought that what rdc85 said is more relevant to the problem, about the CPU's limits.

I have similar problems, E2160 (200x9 = 1.8Ghz) with DDR3 1333 which is running at only 400Mhz DRAM freq (FSB: DRAM = 1:2) thus a data rate of ONLY 800 instead of 1066 or 1333. Foxconn G41MXE motherboard doesnt let me change that 1:2 ratio -- I'm gonna play around again with the bios settings anyhow in case I missed something.

In my case CPU-Z (Memory tab, timings) shows DRAM freq is 400 and FSB : DRAM ratio is 1:2. Due to my E2160's limits I guess there's nothing I can do (except the bit of overclocking of the CPU that I can manage).

SO anyhow, back to OP's problem: to verify what actual frequency his memory is running at, the "Memory" tab of CPU-Z should have it, under "timings", "DRAM frequency"? So if you are right that he is already overclocked, then this DRAM frequency reading in cpu-z would be showing 800Mhz for him, not 400, correct?
!