Good OCing DDR2-800 vs DDR2-1066 and higher

[pavel-]

I am building something or other after July 22nd that I plan to OC on either quality air or water cooling. The specs are roughly:

motherboard: evga 680i a1 or t1
cpu: c2d e6600
video card: 8800gtx or 8800 ultra
ram: ??? (2 or 4gb)

I plan to try and OC the cpu to about 3.4+ ghz, but at first glance I didnt find the FSB and Multiplier ranges for this cpu. Also I am not sure whether the RAM ratio is better to remain at 1:1 or not.

So I am wondering if I should bother spending the extra buck on higher fsb DDR2 or just stick with DDR2-800 and hope it will OC will enough.

What brands am I looking at for DDR2-800 that will OC well? Thanks.

 

[bballsk8er333]

hmm, july 22nd, my birthday

sry, cant help, but i am also wondering about this!

 

[chris1784]

yeah I need to know too, whats a good memory module to buy, i got a GIGABYTE GA-965P-DS3

 

[angelkiller]

Well, keeping a 1:1 FSB is ideal. If you use this FSB:Memory ratio, then to hit 3.4GHz, you need DDR2-756. So if you buy DDR2-800 and use it with a 1:1 ratio, your RAM will actually be underclocked!! So faster RAM isn't necessary for OC'ing.

9x378=3402MHz. 378xDDR2=756MHz

If you really want to OC DDR2-800 with a E6600, you need to hit at least 3.6GHz!! 9x400=3600GHz. An E6600 at 3.6GHz will run DDR2-800 at stock speeds. You can OC the RAM by OC'ing the CPU more from there!!

In conculsion, If you're using a 1:1 FSB, DDR2-800 is way plenty.

 

[chris1784]

hey angelkiller, im a noob here and i'm building my first rig, but later on I plan on OCing it. Can you explain what you mean by the 1:1 ration of fsb and memory? I have a E6320 just in case, what memory do you think i should get, knowing that I wanna OC later on.

 

[bliq]

Correct me if I'm wrong but e6600 is a 1066 FSB part meaning it's running at 9*266 or 2.4GHz. 266FSB is DDR-533.

Upping that to 333FSB yields 9*333 or 3.0GHz. 333FSB is DDR-667.

you want about 3.4GHz but according to the math, you should be good to 3.6GHz at 400FSB, which means DDR2-800.

You don't need DDR2-1066 unless you're planning to exceed 400MHz FSB, which is likely if you're overclocking an unlocked multiplier X6800, but you need to exceed 3.6GHz to need RAM faster than DDR2-800.

 

[pavel-]

The faster the better...

3.6 ghz is a conservative estimate of the e6600 capabilities after they've changed the manufacturing process.

Is the e6600 multiplier locked at 9? So only FSB overclocking is possible?

It is very likely that I will be getting a water cooling kit to push those temps down as well as push e6600 beyond 3.6ghz so I would really like to invest in good ddr2-800 RAM that if asked will go to 445mhz (ddr2-890) or even further if I manage.

Lastly, shouldn't ddr2-1066 run at tighter timings if underclocked? Thus further improving my performance? Thus the question really is, will ddr2-1066 running 450mhz-ish at tight timings really justify its price over ddr2-800 OCed to 450mhz-ish at loose timings?

Thanks for your input.

 

[angelkiller]

hey angelkiller, im a noob here and i'm building my first rig, but later on I plan on OCing it. Can you explain what you mean by the 1:1 ration of fsb and memory? I have a E6320 just in case, what memory do you think i should get, knowing that I wanna OC later on.

Ok. You have two options. You can get DDR-2 with tighter timings, (cas 4) OR you can get get regular DDR2-800, (cas 5) Get whichever is cheaper. Both should give the same results. Reason for this is that if you want 2.3GHz on your E6320, you need a FSB of 333MHz. (7x333=2331MHz) So this calls for DDR2-667 RAM. And the RAM will be running at stock speeds. (And DDR2-800 (Cas 5) will be downclocked to DDR2-667, and Cas will be adjusted to 4) And if you want more than 2.3GHz, you can just OC the DDR2-667, which will not be a problem, as even chepo-RAM will OC a little over their rated specs. (But don't get generic stuff though!)

Ok, now, 1:1 ratio... I don't know what you already know, so I'm going back to the basics. The FSB is what the computer uses to transfer data between the CPU, Northbridge, and RAM. The FSB runs at a defined speed. To get the CPU's speed, the FSB's speed is multiplied by a constant. The constant is the CPU's multiplier. Ok? On Intel motherboards, the FSB is "quad-pumped". I don't know exactly how this works, but reguardless, the FSB speed is multiplied by four to get an "effective speed". That's what you see when you see C2D's with a 1066MHz FSB. The FSB is running a 1066MHz, which is the quad pumped speed. The base speed can be found by dividing it by 4, in which you get 266. OK? DDR2 RAM runs at set speed.. DDR2 also does two "actions" per clock cycle. (Hence the name; Double Data Rate) (The 2 on the end of it signifies the "second generation" if you will, of DDR technology) OK? So to because of this, DDR2 can "effectively" run twice it's actual speed. OK?

Example:
E6320, 1.86GHz, 1066MHz FSB.

So base FSB is 1066/4=266MHz. CPU speed is 266x(multiplier), which is 7. 7x266=1862MHz. Rounded=1.86GHz.

Base FSB=266. You have DDR2-800, which runs at an actual 400MHz. Completely normal. This is where the ratios come in. The FSB to RAM ratio is just that. 266:400=2:3. That's where the ratio comes from. The problem is that when the FSB and the RAM run at different frequencies, they are not syncronyzed. (Obviously) So there is a slight performance loss in the process to get the two out-of-sync frequencies back in sync, so they communicate. To eliminate this why not run the RAM at the same speed as the FSB? That's what the 1:1 ratio does. So if the FSB is 266MHz, the actual RAM speed is 266MHz, which is "effectively" 533MHz, or DDR2-533. So if you change the FSB to 300MHz, you CPU is 7x300=2100MHz, and RAM is 2x300MHz, or DDR2-600. OK?

I'm tired right now, so I probably rambled alot. Sorry. 😳
Try to soak up as much as you can. PLEASE ask any other questions you may have. I'm here to help.

 

[angelkiller]

Correct me if I'm wrong but e6600 is a 1066 FSB part meaning it's running at 9*266 or 2.4GHz. 266FSB is DDR-533.

Upping that to 333FSB yields 9*333 or 3.0GHz. 333FSB is DDR-667.

you want about 3.4GHz but according to the math, you should be good to 3.6GHz at 400FSB, which means DDR2-800.

You don't need DDR2-1066 unless you're planning to exceed 400MHz FSB, which is likely if you're overclocking an unlocked multiplier X6800, but you need to exceed 3.6GHz to need RAM faster than DDR2-800.

Exactly right. Remember you are assuming a 1:1 ratio. You could easily get higher RAM speeds by changing the FSB:RAM ratio. You lose some speed in the conversion, but you also get extra MHz, so it's a tradeoff.

The faster the better...

3.6 ghz is a conservative estimate of the e6600 capabilities after they've changed the manufacturing process.

Is the e6600 multiplier locked at 9? So only FSB overclocking is possible?

Generally the faster the better. Again it's a tradeoff. But at some point, the extra MHz make up for the conversion. Very Good article. Yes, E6600 multiplier locked at 9. But you can lower it though. And also know that a 3.6GHz E6600 is pretty extreme. I'm not saying you can't do it.... Yes DDR2-1066 will run lower frequencies with tighter timings. If two sticks of RAM are operating at the same frequency, the one with the tighter timings will be faster. But is the difference worth the money? I dunno. You decide. (I doubt it though).