Hello everyone,I just spoke with a friend who has stable overclock his C2D CPU by increasing the FSB from 266 to 345. I ask if he can OC further, he said his DDR2 677 has reached the bottleneck level. He said, when we OC the CPU, when need to OC the ram speed as well. Could anyone tell me the calculation different between the 677, 800 and the higher 1066I originally planned to buy the DDR2 800. Just wonder how much benefit can the DDR2 1066 may bring for overclocking performance? It cost a nearly a double in price. If it don't bring much benefit (let the Q6600 OC much more to....>3.6 or even 4), I will go ahead with the 800 as planned.Can I OC the FSB "only" without touching the ram speed, chipset timing and the voltage? Or they have to be change for optimal and stable performance. (Honestly I do not know much about these)Thank you very much!Alkit

Hi AlkitWell when you raise the FSB, the RAM speed increases also. Idealy you will want to have the RAM running at 1:1. So you'll also need to adjust your multiplier correctly. (lower the multiplier+raise the FSB) For example you can get a E6600 running stable at 3.2GHz with your RAM at 800MHz, that would be FSB 400 and your multiplier at x8. In many cases if you go higher than FSB400MHz, you could find your RAM running at 810, 820MHz etc. Now with some added volts to your DIMMS you might be able to reach a stable clock, that is if you have a decent overclockable brand of DIMMS, that said when you reach 2.0v on your RAM (that is IF your RAMM supports upto 2v !!) always have a fan blowing on it because they run hot, but in many cases when you find yourself at the 800MHz setting its for many the limit of increasing the FSB also.. PC-6400 is ok for overclocking, but if you want to go for high FSB ranges id personally opt for PC-8400 PC-1066 with that it'll take you a bit longer before running into the FSB-RAM barrier.Hope that helps a bit

Why is it important to run the RAM at 1:1?Attached is screen shots of my system. Can I improve from here?I am running Patriot PC26400 8000MHZ Andrew

>Why is it important to run the RAM at 1:1?>>Attached is screen shots of my system. Can I improve from>here?>>I am running Patriot PC26400 8000MHZ >>AndrewI have almost the same numbers. On my system, going to 3.2G caused stability problems. I now sit at approx 3.15 and all is good. FSB speed is slightly higher than 1440. CPU temp is around 44c running (using Artic Cooler 7) FS9 (only app that causes higher CPU temps).Scott

Reason is you want to fully utilize everything while still reaching higher speed levels, see you have DDR2 800, now that runs at 400MHz, your not utilizing your full potential bus running it at 355. Also note that you can also raise your rated FSB significantly.So whilst you have your RAM running higher, the rest runs slower, try to get things more equal first 1:1 and work on from there.I'll include a screenshot from one of my others computer i have here, a slightly DDR800 OCed 6600. Note the differences.http://forums.avsim.net/user_files/175682.jpg http://forums.avsim.net/user_files/175683.jpg

If your friend left the RAM divisor on AUTO, then its speed would have increased propotionally as the FSB went up. ie. from 266 to 345 for FSB = from 667 to 865 RAM speed. Looks like auto was using a 2.5 RAM divisor, so see if he can change the RAM divisor from 2.5 to 2. If the RAM was truly the item previously capping out his OC speed, then he should now be able to get up to 432 FSB before it hits 865 RAM speed. Of course, now the CPU or the mobo will likely stop you getting that high anyway, but that all part of the juggle to get the highest OC speed possible. :-lolIn short, the best way to see how high your CPU will go whilst keeping OCs on other components out of the equations for now is to:- set RAM divisor to lowest value (usually 2:1)- set PCI-E clock to 100MHz, PCI to 33MHz (if settable) and AGP to 66MHz (if you even have AGP at all)- set CPU mult to highest available (gives lowest bus speed to help work out OC limit)- incrementally increase FSB and reboot in between until the limit is found.Gary

Sorry guys, I really try hard to understand. But I am still quite confuse with the number and calculation.Let's take the E6600 with DDR2 800 as example:1. Andrew's post withbus speed 355.4Mhz, multiplier 9ram freq: 444.3Mhz2. the second one (from Davis?)bus speed 400Mhz, multiplier 8ram freq: 400MhzHow come the ram freq in first one increase from 400 to 444 (when its bus speed increase from 266 to 355)??And the second one, how come the ram freq can make no change when its bus speed increase from 266 to 400??In the second sample, can we use:bus speed 400Mhz, multiplier "9"ram freq: 400MhzOr the CPU cannot stand for this fast core speed? (too hot)______________________________________________________________________Furthermore, if I put the DDR2 1066 in this example, what can be improved by this given stock bus speed of 533Mhz?A E6600 with DDR2 1066What may the optimum config. to be?I do not think the CPU can operate in multiplier 8 or 9 with FSB increase to 533 and although still keeping 1:1 ratio?I read the other post about DDR2 1066's 4-4-4-12 "better timings at lower speeds"5-5-5-185-5-5-15What does this timing mean to us? and what is the good number to us?Thank you very much for all you guys teaching effort!!!Appreciate it very muchAlkit

Can I play too!?With ram speeds, a good thing to remember is what "DDR" means. DDR means "Double Date Rate." "Well, yea," ya say. "But of what?"The "Front Side Buss." DDR means "Double the Data Rate of the Front Side Buss." The "2" in DDR"2" means nothing (for now).Second, the "XYZ" numbers in the DDR2-XYZ nomenclature are just a speed rating. It tells you how fast the ram can run before it explodes. As described above, the ram's speed is determined by the FSB . . specifically, it runs at two times the speed of the FSB. For example, DDR2-800 ram is rated to run at 800mhz. If you run your FSB at a default 266mhz (Intel's miss-advertised 1066 FSB number), the ram will run at 533mhz. See the math? 266mhz(FSB) X 2(DDR'd) = 533mhz (ram speed). That DDR2-800 will run fine there. It's rated guaranteed to run at 800mhz and is only running at 533. Life is good. Actually there was no need to use DDR2-800 ram here. DDR2-533 would have been fine.This is called running the ram at 1 to 1 (1:1). Actually it's being 2X'd (DDR'd), but this is the default setup. I guess it makes sense to call it 1:1, somehow.Now, lets get fancy. (Disclamer! All Mobos handle this differently, but here's the basic theory. You'll have to interpolate this a bit to get it to make sense on your Mobo. Mfs will totally scramble the ratios presented here. Your only real hope is to actually understand what's going on.)Remember the CPU has a multiplier? Well the ram has one too . . . all it's very own, completely separate from the CPU's. The bios provides a ram multiplier that can drive the ram faster. Ram also has a divider so we can slow it down too. For instance in the example above, I'm using ram rated at 800mhz, but only running it a 533. I might want to increase the ram's speed. If I couldn't use the FSB to drive the ram's speed higher, I'd use ram's multiplier function. Intel generally gives us several to choose from. Let's try one. How about a nice safe 3:4 multiplier (Note: could be 4:3. The manual is your friend.) Here's how it works: In this case of this ratio (relationship), 4 is 25% higher than 3. The FSB speed does not change, but the Ram will be driven as if the FSB actually did increase by 25%. Even though the FSB speed DiD nOt ChaNge, the ram is being drive by the (actual) FSB of 266mhz PLuS a booster of 67mhz (266 X 25% = 67mhz). The ram is being driven by 266 + 66 = 333 mhz. What speed is the ram now running? How about 333 X 2 (DRR) = 666 mhz. Nice ratio. It got us right up to the next standard ram speed rating (fancy that!). But we spent an extra $100 on that fancy ram, and we want it all. Our 800mhz ram is not glowing yet, so let's go some more. We need a bigger multiplier. What is it? heck, I don't know. Get out your calculator! You can do the reverse with the ram divider. If your ram just won't run with your FSB at 1:1 (DDR, or two to one, actually . . . where do they get these terms!), turn it down with the divider. But here's the real take-away. The CPU is your Big Dog. As was suggested, use the biggest ram divider available. In other words, slow your ram down as much as possible to start. You do NoT want your ram to frag out during your initial CPU O/Cing attempts. Turn it all the way down to idle and then lean HaRD on the CPU. Max your CPU out with the FSB. Now try an experiment. Once you get your CPU stable, run some benchmarks with your ram still turned way down. Make a note. Now bring your ram back up. Make another note. Compare.Is all this ram tweaking worth it? Your tell us, but here's what you'll likely find: You will need scientific instruments to see a difference. Ram (OR FSB) speeds will not make a noticeable change in frame rates. You'll need multiple FRAPs runs on a perfectly repeatable racetrack to see an utterly minimal change in FPS. This ram tweaking is all just techie fun . . . and great fun it is.

Darn it Sam - you take all the wonder out of it!!:)Thanx for the explanation - it helps.Vic

Yeah, Agree with all the Sam said, PLUS.. do not forget to run OrthosPrime atleast for 12h to ensure you got a stable overclock found here: http://sp2004.fre3.comGood luck OCing.

Hello Sam,Thank you for you detail explanation about the memory. I just make a new post about my new computer overclocking issue.http://forums.avsim.net/dcboard.php?az=sho..._id=27867&page=I am not sure if it relate to my memory setting. I do think it can handle it, just a problem of my own (how to set it right).Thank you!Alkit

I see you are using Asus's Nvidia 680i board. I've always used Intel chipsets, so this is kinda foreign territory. Here's a good thread going about the Q6600 / G0 on the Asus (Intel) P35 bearlake chipset. It looks like the Q6600 / GO is going to 3.7 on Very good air. The 680i and the P35 are different animals, but the primary voltages (Vcore, ram) and temperatures should be the same. I expect the GO will go to 3.4 on the factory heatsink rig. I agree. You should have some more room to run. Look over the post and see. http://www.xtremesystems.org/forums/showthread.php?t=152722Your target CPU temperature is 71C. Temperature is not an issue till you get there. Intel has designed the chip to run 24/7 at this temp. Notice the post's last stable O/C ran the little guy right up to 69C. That's how you'll finish off your CPU O/C "dial-in." Aim for a tad below 71C. In summer time, you turn the CPU down a bit (warmer ambient). Wintertime, turn it up (lower ambient).Memory: Question, These 680is allow you to simply set a memory speed? It looks that way. If so, the auto-set messed up a memory timing. Look at Cycle Time or "Tras". The memory wants 18 for a DDR800 speed and ol' "autoset" set it to 15. Loosen that up manually if you can. Actually, loosen them all up as much as they will go. This is just for troubleshooting. No luck? Try setting the memory to run at 533. That'll get it off the stop. If you can get the CPU up to ~ 70C, start bringing the memory up. FYI, for future reference, there's better memory than Corsair. My DDR400 will O/C to 402, then it explodes. What a disappointment. Crucial (micron chips) or Patriot (cheap and O/C like a bandit) are on my shopping list this time.

Hi SamA post a just post:http://forums.avsim.net/dcboard.php?az=sho..._id=27877&page=I think my machine actually can get to 3.6 as I just gave it a wild try before. Memory and CPU showing good in POST. However, it doesn't load into window. Is that anywhere need a proportional more power? NB? SB???Temperature, I will try to keep it below 65 at anytime (at the moment). Even I can success to OC it to 3.6G, I think i will keep it at lower like 3.2 for daily use. Unless I know I will fly for whole few days, then I will bump it to higher value. I am sure 3.6G will require other brand coolers. Stock one is not that great for OC when high work load.Memory, I normally set it 5-5-5-15. Although I do not know what it really means. But i see most people setting this value, so i follow. My memory cannot be used as 4-4-4-x as I went to the website and check.http://www.corsairmemory.com/_datasheets/TWIN2X2048-6400.pdfI do not dare to OC my memory, keep it in 400 would be very good to my use. 1:1 FSB 400 , multiplier 9, 3.6G, I will be more than happy if my computer can achieve that!! I have marked down the name you suggest. Thank you!Alkit