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-   -   Core2 overclocking (http://www.hardwarecanucks.com/forum/overclocking-tweaking-benchmarking/2810-core2-overclocking.html)

enaberif October 6, 2007 04:33 PM

Core2 overclocking
 
Since I've now delved into the inner workings of overclocking a core2 I have a questions about the extremes.

1) I know unless you buy a Extreme processor the multiplier is locked but what if you went above the multiplier on a locked cpu, what would happen? Would you fry the chip or damage it? What about an Extreme processor? They say the multiplier is unlocked but how high can you go before it'll damage or not allow the cpu to work?

2) When overclocking you ultimately want your fsb:mem to be 1:1 but it doesn't seem like that is entirely possibly on a Extreme chip. Take this for example...

Example 1
Multiplier @ 10 with FSB @ 1360 (340) = 3.4ghz

Now with memory pc-6400 for example won't run below 400mhz so you can't get a 1:1 ratio.

Example 2
Multiplier @ 13 with FSB @ 1040 (260) = 3.4ghz

Again memory won't run at 260.

So how do you overclock a qx6850 and get a 1:1 or is it even possible?

3oh6 October 6, 2007 04:54 PM

memory will run whatever you tell it to run, going downwards anyway...not sure why you would think PC2-6400 memory won't run at only 340MHz?

also, the whole idea of wanting to run 1:1 is pretty much null and void with the chipsets of today. they run ratios just as well as 1:1 and faster memory frequency, even with looser timings, is almost always faster than the next lower ratio.

enaberif October 6, 2007 05:17 PM

Quote:

Originally Posted by 3oh6 (Post 21607)
memory will run whatever you tell it to run, going downwards anyway...not sure why you would think PC2-6400 memory won't run at only 340MHz?

also, the whole idea of wanting to run 1:1 is pretty much null and void with the chipsets of today. they run ratios just as well as 1:1 and faster memory frequency, even with looser timings, is almost always faster than the next lower ratio.

Well the board I was trying this on wouldn't allow lower than 400mhz :P oddly enough.

3oh6 October 6, 2007 06:42 PM

i think you are misunderstanding what the BIOS is telling you. what do you mean by "it wouldn't allow lower than 400MHz..."? did the system not boot with the memory set to 1:1 at 340FSB? what board are you referring to?

pscout October 6, 2007 06:46 PM

Without an extreme model you can only lower the cpu multi within the supported range. On a 6600 default is 9 and you can lower it to 7 on most mobos manually.

If speedstep (aka eist) is enabled it will lower vc and multi automatically under low load to save energy and reduce heat. You want to disable eist and c1e when you overclock. EIST if enabled, will not let you adjust vc, at least not on any intel chipset mobo i have used.

I have never used an nvidia chipset mobo with c2d and c2q but i thought they would let you run memory lower than 1:1 ... ie independent of fsb? Other than supporting sli, that was about the only advantage they have over intel chipsets.

If you are running 6400 memory, there should not be a need to run the memory at less than 1:1. 400 fsb at 1:1 will be running 6400 memory at stock speed on intel chipsets. I assume the nvidia runs dual channel so it should be the same.
Not sure how well 4gb of memory will oc beyond stock especially if it is 4x1gb sticks. All my rigs are 2 sticks of 512 or 1gb.

enaberif October 6, 2007 08:33 PM

Quote:

Originally Posted by 3oh6 (Post 21607)
memory will run whatever you tell it to run, going downwards anyway...not sure why you would think PC2-6400 memory won't run at only 340MHz?

also, the whole idea of wanting to run 1:1 is pretty much null and void with the chipsets of today. they run ratios just as well as 1:1 and faster memory frequency, even with looser timings, is almost always faster than the next lower ratio.

Actually I just did some synthetic tests with everest and running 1:1 did yield better performance then when I was not.

But one of my original questions still wasn't answered.. what happens if you were to use a multplier higher than what the cpu is rated at... would it damage it?

sswilson October 6, 2007 09:00 PM

Quote:

Originally Posted by enaberif (Post 21633)
Actually I just did some synthetic tests with everest and running 1:1 did yield better performance then when I was not.

But one of my original questions still wasn't answered.. what happens if you were to use a multplier higher than what the cpu is rated at... would it damage it?

The CPU will not accept a higher multiplier than stock.

That's the difference between the "uber" procs and those for us normal folks.... the highest end chips do not have their multipliers locked to prevent them from being raised, while the lower end ones only allow you to drop the multiplier downwards.

enaberif October 6, 2007 09:20 PM

Quote:

Originally Posted by sswilson (Post 21634)
The CPU will not accept a higher multiplier than stock.

That's the difference between the "uber" procs and those for us normal folks.... the highest end chips do not have their multipliers locked to prevent them from being raised, while the lower end ones only allow you to drop the multiplier downwards.

Ok but what about an extreme chip.. they are unlocked so could you possibly raise the multiplier too high?

pscout October 6, 2007 09:24 PM

Quote:

Originally Posted by enaberif (Post 21636)
Ok but what about an extreme chip.. they are unlocked so could you possibly raise the multiplier too high?

I am sure if you raised the multi too high it won't post.

From what i have seen, the highest oc's from these extreme cpus is normally at a lower multi than the defaults.

enaberif October 6, 2007 09:50 PM

Quote:

Originally Posted by pscout (Post 21637)
I am sure if you raised the multi too high it won't post.

From what i have seen, the highest oc's from these extreme cpus is normally at a lower multi than the defaults.

Yah I've seen 333x9 oddly enough! But hey whatever works!

And good to know that it would still work.


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