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Windows 7: ddr2 pc2 6400 u running at 333?

23 Nov 2010   #1
lecky2009

windows 7 ultimate x64
 
 
ddr2 pc2 6400 u running at 333?

HI there newbie here i have just installed 3gb of ddr2 800mhz. it originally had 1gb pc2 5300u. but is showing speed in cpuid as 266 mhz i checked in bios and my dram freq was showing 532 mhz double what it showed in cpuid so i set it to 800mhz in bios and windows wouldn't start so i rebooted and dropped it to 666mhz giving me 333mhz in cpuid is this correct as i thought it should show as 400mhz? my mobo is a original acer with flashed modded bios so i could adjust cpu and ram freq

any advice would be much appreciated

ddr2 pc2 6400 u running at 333?-ram.png




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23 Nov 2010   #2
pparks1

Windows 7 Ultimate x64
 
 

When you are dealing with DDR ram, it's double data rate. Thus....DDR2-800Mhz is RAM that "when doubled' runs at 800mhz....but it's standard front side bus speed is 400mhz.

With PC's, the CPU's run at a certain front side bus speed and then have a multiplier. Therefore, a chip like an Intel Core 2 Quad Q9550 runs stock with a 333mhz front side bus and an 8.5x multiplier. Thus, true speed is 333 x 8.5 or 2.83ghz. In a case like this, the default speed the RAM would run is 333 x 2 (since it's DDR)....so RAM would run at 667mhz. It doesn't matter whether you install DDR2-800, DDR2-1000, or DDR2-1200....it's going to run at 667mhz because it's effectively 2x the speed of your front side bus.

So, with an Intel Q9550...if you wanted your RAM to truly run at 800mhz...you would HAVE to increase the FSB speed of your CPU to 400mhz......but be aware when you do this, your CPU now runs at 400 x 8.5 or 3.4ghz. You are now overclocking and have to worry about heat and stability.
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23 Nov 2010   #3
lecky2009

windows 7 ultimate x64
 
 

Thanks for the advise m8 i get it now Ive ordered another 2gb of ram the same brand as the 2g installed so it should run dual channel do you think that will make a difference to the performance?
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23 Nov 2010   #4
chev65

Windows 7 Ult, Windows 8.1 Pro,
 
 

Quote   Quote: Originally Posted by lecky2009 View Post
HI there newbie here i have just installed 3gb of ddr2 800mhz. it originally had 1gb pc2 5300u. but is showing speed in cpuid as 266 mhz i checked in bios and my dram freq was showing 532 mhz double what it showed in cpuid so i set it to 800mhz in bios and windows wouldn't start so i rebooted and dropped it to 666mhz giving me 333mhz in cpuid is this correct as i thought it should show as 400mhz? my mobo is a original acer with flashed modded bios so i could adjust cpu and ram freq

any advice would be much appreciated

Attachment 116948
Actually you do not need to overclock your CPU in order to run the memory at a higher or even the default Mhz. You only need to change the divider ratio between the FSB and memory. I think that pparks forgot that most boards with overclocking bios have many dividers to choose from.

You normally would need to change the memory from Optimal to Expert settings in order to get the divider ratio list" this setting is a bit different for all boards". You should have more options for dividers then.

On some boards bios you can also set the memory speed to where you want it and the board will set up a divider automatically. The problem is that certain dividers are more stable than others so it's best to use the dividers the board already has.

As it stands you are using the 8:10 divider which would need to be changed.
A Memory divider is a ratio which is used to determine the operating clock frequency of computer memory in accordance with Front Side Bus frequency, if memory system is dependent on FSB clock speed. Along with memory latency timings, memory dividers are extensively used in overclocking memory sub-system to find stable, working memory states at higher FSB frequencies. Memory Divider is also commonly referred as "DRAM:FSB Ratio".

I see that your E2160 is already overclocked from 1.8Ghz to 2.4GHz. The default FSB for your CPU was already at 800MHz before you overclocked the FSB. Because you overclocked that all changed and so did the required divider to put your memory at 800Mhz.

Your bios should have a stable divider that will put your memory at 800MHz without having to change your FSB overclock setting.

So basically you need to look for a divider that gets your memory back to 800MHz. Remember the bus runs at 1/2 the memory speed so it will show up as 400Mhz in CPU-Z.

Info on your CPU > http://ark.intel.com/Product.aspx?id...es=SLA3H,SLA8Z
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23 Nov 2010   #5
unifex

Windows 7 Ultimate (x64)
 
 

To add to the great information above, if you have memory DIMMs of different frequency - say PC2-5300 and PC2-6400, then the system will perform at the lowest frequency, in this example at 333 MHz - or data rate 667, as explained by pparks already.
My System SpecsSystem Spec
23 Nov 2010   #6
lecky2009

windows 7 ultimate x64
 
 

thanks for the advice ppl i cannot find a divider option in my bios possibly because its unlocked acer bios it doesnt have some of the options of retail boards i think iam going to run 4gb of same make ddr2 at 666mhz seams to run fine
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23 Nov 2010   #7
pparks1

Windows 7 Ultimate x64
 
 

Quote   Quote: Originally Posted by chev65 View Post
I think that pparks forgot that most boards with overclocking bios have many dividers to choose from.
I didn't forget it....but I always like to keep a 1:1 ratio on my CPU and memory. I would prefer to run the RAM slower at a 1:1 ratio that faster at say a 4:5 memory divider. For fairness, I should have mentioned that to let the other person decide what they were comfortable with.

As it stands, with an Acer board...you aren't going to be able to overclock or change these settings. The mfg usually locks all this stuff down so that you cannot blow up the machine or components that they warranty.
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 ddr2 pc2 6400 u running at 333?




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