Trying to understand why RAM freq is so low.

[NoIdea]

First off here are the relevant specs (everything running at stock):

MoBo: Asus P4PE-X

CPU: Intel® Pentium® 4 Processor 2.80 GHz Northwood FSB 533MHz

RAM: Xerox (Samsung) 1024 mb DDR PC2100 266MHz

CPU-Z Stats:

CPU Tab:
Core Speed ? 2806 MHz
Multiplier ? x 21.0
Bus Speed ? 133.6 MHz
Rated FSB ? 534.5 MHz
Voltage ? 1.584 v

Memory Tab:
Freq: 133.6 MHz
FSB : DRAM ? 1:1

SPD Tab:
Module Size: 1024 mb
Max Bandwidth: PC2100 (133MHz)

My question is why is my RAM only running at 133MHz? Doesn?t the freq. of you RAM runs at is 2 * FSB. If so then my ram should be 133 * 2 = 266. I don?t understand, my RAM is PC2100 and my mobo supports this type. I even went into BIOS and changed the RAM freq from ?auto? to ?266? MHz. But still I see 166 when I run CPU-Z. Do I have to set my board to JumperFree mode? If so the manual doesn?t say how. The only reference to jumpers is how to disable keyboard wake up feature. Could someone provide me with a brief explanation and possible solution to get my RAM running at 266?


Much appreciated

 

[SparkyJJO]

Think of it like a CPU - there is the bus speed then the multi of the CPU which equal then the total CPU speed. The RAM has a 2X multiplier if you want to think of it that way. Technically the RAM is only running at 133MHz but the DDR makes it an apparent 266MHz. That is my understanding of it.

 

[Conky]

Your RAM is running at the correct speed.

You need to consider the whole Intel "quad-pumped" FSB thing... 133.33 x 4 =533.33. 😉 And if that wasn't confusing enough... it being DDR or double data ram means it should run at 266 although since it's DDR it's still at 133 as far as true frequency or 266 in the bios settings. This linked article gives you a place to start figuring this out.

It's all terribly confusing but your RAM is running at the right speed. :thumbsup:

 

[StopSign]

- Real Intel FSB = rated FSB / 4
- Real AMD FSB = HyperTransport / 5 if rated is 1000, HyperTransport / 10 if rated is 2000
- Real DDR memory speed = rated speed / 2

Hope that's crystal clear now.

 

[NoIdea]

Originally posted by: StopSign
- Real Intel FSB = rated FSB / 4
- Real AMD FSB = HyperTransport / 5 if rated is 1000, HyperTransport / 10 if rated is 2000
- Real DDR memory speed = rated speed / 2

Hope that's crystal clear now.

You mean

- Real DDR memory speed = rated speed *2

Thanks Everyone

BTW since my RAM is only PC2100. Is ther eany point in OCing the CPU?

 

[StopSign]

No, I meant what I wrote.

 

[Roguestar]

Originally posted by: NoIdea

Originally posted by: StopSign
- Real Intel FSB = rated FSB / 4
- Real AMD FSB = HyperTransport / 5 if rated is 1000, HyperTransport / 10 if rated is 2000
- Real DDR memory speed = rated speed / 2

Hope that's crystal clear now.

You mean

- Real DDR memory speed = rated speed *2

Nope, DDR rated for 533Mhz actually runs at 266Mhz, and sends data twice per cycle (hence double data rate, and why the "effective speed" is twice the actual frequency).

 

[StopSign]

I'm sure you meant 266. It's okay.

 

[Roguestar]

Ssh! Don't broadcast my shame!

I'm trying to work and post on forums at the same time 😉.