Memory dividers, high fsbs vs high multis

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prasvt

Gawd
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Mkay, in the process of helping someone try to oc (and also for my own oc aspirations), I'm wondering about a few things.

1) Is it better to keep a 1:1 fsb:dram ratio? I know w/ my mushkin PC8500 ram, the people at mushkin suggested 1:1.2 ratio w/ the Abit P35 mobos - of course that's maybe a special circumstance.

2) RAM divider issues aside (or not if that's the case), is it better to use a high fsb or a high multi? 400 x 9 or 360 x 10 for example?

3) Wouldn't a higher fsb require more mch voltage in addition to whatever additional vcore is needed for the overall overclock?
 
Higher FSB is better.

Get the max FSB you can with your RAM at 1:1.. then, if you have enough headroom with the RAM, raise it to 1:1.2 or whatever you can without loosening the timings any more.

With current Intel stuff, you gain very little throughput on the RAM if you run it above 1:1.

When they move to an on-die memory controler, it will most likely be different however.

As long as you have good airflow in your case and good chipset cooling, you won't need that much more mch voltage... .1 to .2 maybe.
 
Well i bolt modded the chipset heatpipe coolers on my ip35 pro, replaced the thermal paste w/ TX2 and added 40mm fans to the pwm and nb ..+ w/ water cooling, system temps are a bit lower. Airflow is good.

Hmm..ok well right now I'm at 360 x 10, 1.565V bios which translates into 1.51-1.53 in windows.
sb 1.5 is at 1.6
NB is at 1.56
SB is at 1.09
Vtt is at 1.42

It's possible that I could let off on the Vcore a little (not that my temps are high or anything).

So at 450+ fsb is 1.56V enough for the northbridge?
 
It's possible that I could let off on the Vcore a little (not that my temps are high or anything).
Click to expand...

C2D's will just shut themselves down if getting dangerously hot. There is no protection from over voltage. Your Vcore is too high IMO, but its your stuff do what you want.



So at 450+ fsb is 1.56V enough for the northbridge?
Click to expand...

MCH/northbridges are like CPU's, no two are the same. I am assuming you made a typo and intended; 350+ fsb ...


You should be stability testing and get both of those as low as you can once you determine you target OC, or working the other way, determine your max Vcore and Vnb limits and see how fast you can make it go and still be stable.


Intel absolute max per data sheets are 1.55V for the cpu and 1.375 for the mch.

A memory multiplier of about 1.5 will run your memory very near its spec.

To calculate a target memory multiplier use 1066 divided by ( FSB x 2), try the closest but lower available multiplier first, then see if the closest but next highest available multiplier will work.
 
No, I'm running 456 x 8 right now..below 400fsb (360 x 10, 400 x 9) I had the mch voltage around 1.45 or so. Under load the cpu is only getting about 1.46V. Yeah 1.52 is a little high but it's still idling around 30c and about 50c under load. The RAM is running at about 1092 and has been pretty rock solid up to this point.

So 1.375 is the max - are you referring to Quads or Dual Cores? i guess I can give that a shot...one thing I noticed is that running the fsb at 400 or 450 increases memory performance by about 20%. I ran all the benchmarks in everest and generated reports ..memory read/write/copy were alot faster at higher fsb. All the cpu/fpu test results were marginally higher. Otherwise, the computer seems equally stable at any combination yield 3.6ghz.

BUT, admittedly I haven't spent the time to test lower voltages so I'll do that. I think the lack of heat may improve things.
 
the 1.375 is for the mch/northbridge voltage. This is the Memory Controller Hub, also called the Northbridge and it is under the heatpipe heatsink about in the middle of the board, so its the same part regardless if you use a quad or a dual. If you modded the heatpipe and put a fan on it you can push it fairly hard. A lot of people greatly exceed the Intel max on the MCH/northbridge, I am not recommending you do, but they seem to stand the voltage ok based on a lot of user posts.

Glad to see you got the cpu voltage down, they are not so forgiving. Sounds like you did a nice job preping that board to be able to get those stable high FSB numbers. Should be a winner.
 
Well I lowered some of the voltages and went back to 360 x 10:

Vcore 1.47 in windows idle
MCH voltage 1.36
CPU Vtt 1.35
And a notch up on both SB voltages

Ram is running 1:1.5 = 1080mhz

I still need to run prime95 for a while, but the machine's been playing Mass Effect for a few hours w/o any hitches.

Yeaaah I decided to prepare the board for overclocking this time around. No point going through the trouble of watercooling when the chipset ICs are heating up.

PWM temps are a good 20 degrees lower now (in 70s max as opposed to pushing 90C before), and cpu temps are of course down so I think I'm finally satisfied.
 
Heres' a question. What's better, 400x8 at 1.37volts and ram at 1:1. Or 340x10 at 1.45volts and ram out 5:6 409mhz?

I want too try and get the best performance. How can I tweak my ram too be better when at 340?
 
Well if your ram is at 340 (or 680 effective), you can tighten the timings at a lower speed and that tends to help a little.
 
Dude you keep posting voltage numbers, please mention if you are talking NB voltages or CPU voltages. lol.

First off double check all intel thermal management and power conservation technologies are off, namely C1E and speed step. I'm assuming its the Abit in your sig, but for anyone reading if your running an Asus or Gigabyte motherboard you gotta turn of EPU (and whatever the other company equivalent is) off. Also make sure your in OS power management stuff is set to never hibernate and never undervolt.

Now that thats out of the way, the 1066MHz fsb has been proven to choke a quad core CPU, as is the case with the Q6600, so you want to remove that bottleneck. That said, when your in the 400MHz + range, I don't think you need to worry about it. Its also generally easier to overclock using the multiplier rather than the FSB because your northbridge will tend to tap out faster than your CPU. So i'd suggest pushing for high 300's/low 400's + 10X multiplier. If you can hit over 4GHz you should be happy. If your on a liquid loop, I think you can do it too.

As for voltage, I wouldn't go past a 1.55 Vcore (after removing Vdroop factor) myself, but that's your choice. Extended periods of 1.53V might have been what killed my 680i board (RIP). Then again, the months that I ran with that gobilly-goop they put on the underside of the NB HS/F mighta had something to do with it. That was really terrible.

As for your NB voltage I think I've got my X38 (which I dont like btw, go with a DFI P35 if your an OCer, stay the hell away from the ASUS ROG line if you can) running at 1.4. I havn't had done enough research into what its capable of though. I'd imaging P35 NB silicon is similar if not identical to X38 NB silicon.

As for ram, I wouldn't put any thought into its speed until you've figured out just how hard you can psu your CPU. run 1:1 until you've got your max CPU speed, once you've got that, you can push your ram. Over and over again reviews have shown us high latences + high speed is a better idea than low latencies + low speeds. I would go to Cas 7 or 8 if it means you can break 1200MHz with your ram. Its what DDR3 is doing and I dont think anyone here would argue DDR3 is slower in any case than DDR2.

Hope that helps.
 
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