OCing e6700 w/ 800 Mhz RAM: Lower multiplier or mem timings?

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RichardJSampson

RichardJSampson

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Aug 23, 2001
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In overclocking my CPU, it seems that the maximum speed that will pass Prime95 for several hours is around 3.42 GHz. Somewhat dissapointing. I still think, however, I should be able to ultimately make it to 3.6, which is my goal at this point.

vCore and FSB are at 1.4v and memory is at 2.1v (factory specified). Specifically, the modules are Corsair "Xtreme Performance" XMS2-6400C4's. These are timed at 4-4-4-12-4.

I got these because I had high hopes of coming close to 400 MHz FSB, but that seems like a pipe dream now (or is it?).

So, with 800 MHz RAM running at about 690 MHz, I feel like I'm missing out on speed.

Would it make sense to lower the multiplier to 8 or 9 and raise the FSB to 400? If not, can I reduce the some of the latency timings to 3 because the memory is running below its factory-designed speed? Or -- is the answer none of the above and just keep the memory where it is?
 
Set your fsb to 360 and Vcore to 1.575
Set your ram at 5 5 5 15 then play with the timings after you get the clocks your after
Did you read wusys guide?
I don’t know what kind of cooling you have so you may be stuck at lower clocks.
Not all the cpus clock the same and if your cooling is inadequate you’ll never maintain your goal
 
Hi kwalker,

I appreciate your response. I have indeed read wusy's guide, and I've looked at several other resources as well.

My cooling solution is air-based, and is a Zalman CNPS9700 LED (note that this isn't the CNPS9500). I have tested several coolers (including the Big Typhoon) and find this to be a cream-of-the-crop air cooler:

zalmancnps9700led3h.jpg


I will try increasing the voltage, but what good could it do increasing my timings to 5-5-5-15 when they are designed to operate in 4-4-4-12 at 800 MHz? Based on your signature, I see you have DDR2 667 RAM, so I could see why that would make sense on your rig, but it seems to me like it could only slow mine down unnecessarily. Then again, you've got two processors listed in your sig, so I'm not sure what your setup is. The link you provide shows a crazy overclock. What is your cooling solution?
 
its just to get you started
Click to expand...

Looks like we're writing in real time. I actually edited my response to you while you responded.. the reason being that your signature link shows a crazy overclock. With what are you cooling your 6600 to get to almost 4 GHz?
 
Hi kwalker,

I appreciate your response. I have indeed read wusy's guide, and I've looked at several other resources as well.

My cooling solution is air-based, and is a Zalman CNPS9700 LED (note that this isn't the CNPS9500). I have tested several coolers (including the Big Typhoon) and find this to be a cream-of-the-crop air cooler:

zalmancnps9700led3h.jpg


I will try increasing the voltage, but what good could it do increasing my timings to 5-5-5-15 when they are designed to operate in 4-4-4-12 at 800 MHz? Based on your signature, I see you have DDR2 667 RAM, so I could see why that would make sense on your rig, but it seems to me like it could only slow mine down unnecessarily. Then again, you've got two processors listed in your sig, so I'm not sure what your setup is. The link you provide shows a crazy overclock. What is your cooling solution?
Click to expand...

obviously youve never seen or used a tuniq tower 120?
 
its just to get you started
Click to expand...

Looks like we're writing in real time. I actually edited my response to you while you responded.. the reason being that your signature link shows a crazy overclock. With what are you cooling your 6600 to get to almost 4 GHz?

ummmm dont you mean pentium d 920 (2.8ghz Pentium D)?
 
its just to get you started
Click to expand...

Looks like we're writing in real time. I actually edited my response to you while you responded.. the reason being that your signature link shows a crazy overclock. With what are you cooling your 6600 to get to almost 4 GHz?

ummmm dont you mean pentium d 920 (2.8ghz Pentium D)?
look a little lower
 
I think we're kind of getting away from the original question, as we're focusing right now on how to increase speed in general.

Let's assume for a moment (and I hope this isn't true), that my CPU maxes out at 3.43 GHz (this is the highest speed that's passed prime95).

My question is this: Should I lower the multiplier from 10 to 9? This will result in the same stable speed (3.43 GHz), but the RAM and FSB will be running faster. So with speeds being equal, is there something to gain with the memory running faster?

And if not: Can I lower the timings from the stock 4-4-4-12 to something like 3-3-3-8 because my memory is running slower than the speed for which it was designed?

Thanks for the help :)
 
You can lower to 9X400 for 3.6 but you will loose a little ground in performance. (Test with superPi mod and sisSandra 2007)
The 10 X multiplier is where you should start.
Just up your voltages until you’re stable and if you start hitting 62C you’re about maxed out temp wise with that cooler.
My E6700 stopped at 3.6 GHz and wouldn’t go any further on this board but 3.8 on another.
Every component has its own personality.
Just a pointer 1.55 is absolute max for the CPU according to Intel datasheets.
With air cooling you need to pay closer attention to your temps at higher volts.

at 9X your going to push the limits a little with that board.
it hits a wall sooner than the p5b deluxe fsb wise.
that will hold you back thats why I say try 10X first
 
OK, I'll stick with the current multiplier. I tried going up to 1.45 volts at 350 MHz vCore, and it failed Prime95 in about 10 minutes. I then upped it to 1.50 and then it failed in about 2 minutes. In both tests, the maximum temperature was 56 degrees. So I don't think I'm being limited by temperatures. What else could it be?
 
pull out two gigs of that ram and test your oc.
also your vcore can come up a little because bios settings and actual vcore output varies(droops)
my board for instance vcore set 1.575.
actual reading with dvm 1.48
just stay away from anything over 1.55
 
Definitely try relaxing your memory timings to 5-5-5-15 and/or boosting DIMM voltage - looser timings won't undermine a higher stable overclock. Try memtest86 or RightMark Memory Analyzer to see if it's stable. It's all in Wusy's guide.

Have you changed any other voltage settings on the board, like the chipset?
 
I had trouble hitting 400MHz FSB with my DS3 and 6400 until I backed off the FSB and MCH voltages to normal.

With the FSB and MCH voltages upped like in wusy's guide (before the final "backing off" stage, of course), I was having huge problems breaking 375 FSB (as in, immediate crash after POST), but she's steady as a rock at 400 now, and I'm sure I could go higher.
 
Well I'll never get to 400 MHz without serious cooling (someone needs to market a freon-based system!) but I would at least like to get to 365. What voltages are you using? And incidentally, when I backed off the timings to 5-5-5-15, the system failed Prime95 much earlier.

Now most people don't have 4gb of RAM (as XP doesn't support much more than 2 gigs), so having 4 modules, would I still use the same voltages as people would use for 2 modules? I tried upping it a bit and it didn't seem to have any appreciable effect.

I know OCing has a huge luck component, but certainly a 6700 should be able to do better than 3.45 GHz? (At 3.45, max Prime 95 load temp is 54 degrees). I feel gyped, like Intel sold me a 6600 they binned as a 6700 🙁
 
in Chipset section of the bios
Hyperpath 3 set to Disable
SPD timings option set to Enable
raise Vcore voltage to 1.5 -- 1.55
the P5W DH board has fsb walls at around 300 and some around 360.
you have to force the 1066 fsb strap.
raise the north bride voltage slightly(not to the maximum)disableing hyperpath3 should help keep those volts down
try with only two gig of ram .
what are your voltages in the windows envirnment @ 3.4ghz?
 
I think we're on to something here..

Hyperpath 3 has always been disabled, but so has SPD timings. By simply enabling it, Prime95 has been running so far for 10 minutes at 3.55 GHz. Usually it craps out after 1 or 2 minutes at 3.5 and above. I've set Vcore to 1.50 for the time being.

Interestingly enough, CPU-Z is showing a stable Vcore of 1.213v. Normally it fluctuates between 1.2 and 1.41 during testing. That SPD timing option really seems to be the silver bullet here! Thanks for the help! Incidentally, the max load temp is about 58 degrees. I think I'm starting to get close to my thermal envelope. I haven't removed any RAM yet.

Oh by the way, Wusy recommends running DUAL instances of Prime95. Are you guys actually doing that???

EDIT: WOW! Now I'm stable at 3.7 GHz! With the air conditioner on, my load temps are 54 degrees! That SPD option was the key! Looking at Wusy's guide, that's what he called for, but I misread it as it were.

Anyway, since the BIOS is throttling the timings, the RAM is running at 5-6-6-18 according to CPU-z. Well that's the best situation. Am I better off throttling back to a speed (the 3.4 GHz) where I can run at 4-4-4-12, or does the increased clock speed compensate for the slow memory timings?
 
glad to see your going in the right direction.
Yes we use two instances of prime 95.
or Orthos set at priority 9 for heavy stress .
youll see your thermal threshold better with both cores burning.
your ram timings will be addressed after you find your max stable clocks and still maintain less than 61 C or right at 61.
the ram is going to take some voltage increases up to 2.4 and a fan blowing on those modules to protect your investment.
leaving them be is fine if your ok with the bandwidth decrease.
running two modules will run lower latency timings in most casess at higher clocks with lower voltages.
Make sure your psu is up to this task .
You still havent told me what operating system your useing.
its good to list all your specs to get the right help.
cheers 8)
 
Oh sorry about that; XP Pro SP2 is my OS.

I'm not tremendously worried about the PSU, a thermaltake toughpower 750watt should take pretty much everything that gets thrown at it.

The memory is Corsair "xtreme performance" XMS DDR 6400 modules. They have sinks on them, but not the really killer ones some of their other modules offer. Do you guys just ghetto a fan onto your modules?

I'll try running dual instances of Prime95 after work, and then we can work on the memory timings issue.
 
you have to have XP Pro 64 bit Server 2003 or vista to utilize 4 gig of ram.
take out two for now for dual channel and your timings can come down
 
Yeah I know I need Vista.. I do have a trial version (but it's only 32 bit). Is it worth installing it? Also, I understand that by using the /PAE and /3gb strings in the boot.ini of XP Pro, up to 3gb of RAM can be addressed (although XP Home apparently doesn't have this capability.

Can anyone confirm?
 
Yeah I know I need Vista.. I do have a trial version (but it's only 32 bit). Is it worth installing it? Also, I understand that by using the /PAE and /3gb strings in the boot.ini of XP Pro, up to 3gb of RAM can be addressed (although XP Home apparently doesn't have this capability.

Can anyone confirm?
Click to expand...

this should get you in the right direction
http://www.microsoft.com/whdc/system/platform/server/PAE/pae_os.mspx
 
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