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Noob ? ram's role in OC

post #1 of 3
Thread Starter 
Ok,

I've done a lot of research but still can't get a handle on the role RAM plays in OCing??!!!

The basics I got from Fade2Green514 (OCN member) in a different thread: the following refers to a Gigabyte d/s3 and e6300

"basically heres how it works
you use a base speed to figure out the rest of the clocks in your computer.
for core 2 duo's this speed is 266
base speed * 4 = fsb (in your case 266*4 = 1066)
base speed * cpu multiplier = cpu speed (your case 266 * 7 = 1.86ghz)
im not sure how it works for ddr2 and intel memory controllers, but it also uses the base speed to determine memory clock as well."

Now that all makes sense to me. to start OCing you bump the base speed up until the system is unstable . . . so just for a sample say I bring it up to 300
fsb . . . 300 x 7 (multiplier) = 2.1Ghz Got it, but when does the RAM come into play?


Questions:

1. What I really want to know is where the ram comes into play, DDR2 ram. How does ram speed affect the OC? ddr2 667 and ddr2 800? some equations would be nice, I think better in numbers than in words (=

1a. What’s up with the nomenclature of ddr2?? 667 can be either pc2 5300 or 5400? ddr2 800 = pc2 6400??

2. Random question: why does the board list that it supports fsb 1066/800/533. 1066 can't be the limit of the board otherwise it would not be able to OC right?

2a. Is the unit of measure for the fsb mhz, is this also the same used for ddr2 (only divided in ½) ie. 667 = 1334mhz?

My assumptions:
Ddr2 667 will run on a 1:1 with 1334 fsb (being double data rate 667 actually 1334)
1334 / 4 = 333.5 base speed
333 x 7 = 2.3 Ghz
so with ddr2 667 at stock speed your biggest OC you can attain will be 2.3Ghz?

I’m having fun learning all this stuff but this RAM question I was unable to find an article or post that answered it for me.

I love OCN, thanks for all you help in advance. If anyone wants to check out my planned build and give some feedback I’d also appreciate it. http://www.overclock.net/intel-build...rig-build.html
post #2 of 3
Quote:
Originally Posted by jambodan
1. What I really want to know is where the ram comes into play, DDR2 ram. How does ram speed affect the OC? ddr2 667 and ddr2 800? some equations would be nice, I think better in numbers than in words (=
RAM plays an important role in overall system performance, and thus in overclocking as well. The general explanation about FSB and base speed is correct. And you assumed correctly that you divide the RAM speed by two to compare it with the base speed. Thus, the DDR2 RAM matching the base speed of the Core 2 Duo is DDR2 533 (both have a base speed of 266MHz). Now, in most BIOS-es, you set the RAM speed to what you want it to be, and then increase your base speed of the CPU. Thus, when setting RAM at DDR2 533, and increasing your FSB to, say, 320 MHz, your RAM will effectively run at 320/266 x 533 = DDR2 641 speeds (base speed = 320)

Quote:
Originally Posted by jambodan
1a. What’s up with the nomenclature of ddr2?? 667 can be either pc2 5300 or 5400? ddr2 800 = pc2 6400??
The number behind DDR indicated the frequency, while the number behind PC2 indicates the estimated bandwidth. Some manufacturers estimate a bandwidth of 5400 for DDR2 667, while others are more conservative. I guess it's just rounding, and marketing.

Quote:
Originally Posted by jambodan
2. Random question: why does the board list that it supports fsb 1066/800/533. 1066 can't be the limit of the board otherwise it would not be able to OC right?
The max. supported speed is the max supported RAM speed with everything at stock! Obviously, when overclocking you can exceed that speed, but hey, overclocking it never listed as supported (check the AMD socket 939 boards, which list DDR 400 as max speed, while many folks use DDR 500)

Quote:
Originally Posted by jambodan
2a. Is the unit of measure for the fsb mhz, is this also the same used for ddr2 (only divided in ½) ie. 667 = 1334mhz?
This is correct.

Quote:
Originally Posted by jambodan
My assumptions:
Ddr2 667 will run on a 1:1 with 1334 fsb (being double data rate 667 actually 1334)
1334 / 4 = 333.5 base speed
333 x 7 = 2.3 Ghz
so with ddr2 667 at stock speed your biggest OC you can attain will be 2.3Ghz?
This means that at a base speed of 333MHz, DDR2 667 will run at stock speeds when set to 1:1 with the CPU. Generally, RAM can handle more (overclocking ) and can run faster. Depends on the quality of the RAM
    
CPUMotherboardGraphicsRAM
E8400 @ 3.8 GHz DFI LANPARTY DK X38-T2R eVGA 8400GS 2GB Mushkin DDR2 800 (single stick) 
Hard DriveOptical DriveOSMonitor
250GB WD SATA None Windows XP Pro 32-bit HP Pavilion f1703 
KeyboardPowerCaseMouse
N/A Corsair HX520 Coolermaster Cavalier N/A 
Mouse Pad
N/A 
  hide details  
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CPUMotherboardGraphicsRAM
E8400 @ 3.8 GHz DFI LANPARTY DK X38-T2R eVGA 8400GS 2GB Mushkin DDR2 800 (single stick) 
Hard DriveOptical DriveOSMonitor
250GB WD SATA None Windows XP Pro 32-bit HP Pavilion f1703 
KeyboardPowerCaseMouse
N/A Corsair HX520 Coolermaster Cavalier N/A 
Mouse Pad
N/A 
  hide details  
Reply
post #3 of 3
Thread Starter 
Wow this is GREAT.

I really appreciate the help, I feel I've got it down now. I guess I was not as far off as I felt I was =)

But I now know why 800 is so much better than buying 667 RAM I was clueless before your response, glad I found out now and not after I had bought my 667, boy would I have been disappointed.

Thank a lot,

and thanks for checking out my planned rig, I had seen your many posts on threads similar to mine and really liked your input so I was really glad when I saw you post to my thread (=

I do live in cali and checked out monarchcoputer.com but their selection is . . . a little less than amazing. Do you know of anything comparable to newegg that is not run out of cali? It would save me close to $70 in tax!!!
In the spirit of trying to keep on topic here's the link to that thread.

http://www.overclock.net/intel-build...rig-build.html
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