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Intel CPU 2.66GZ E6750 Compatibility

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September 14, 2007 6:13:52 AM

Will this chip work in my Intel motherboard? It's a D975XBX2. As I understand it the E6750 has a fsb of 1333hz and the mb is 1066hz.

So will the mb just use the cpu at 1066 or just not work at all?
September 14, 2007 6:47:29 AM

Hopefully, the CPU will just run at 1066 FSB with a core speed correspondingly reduced to 2.13GHz, but it might have intermittent problems.
September 14, 2007 12:04:17 PM

hopefully your motherboard will have a bios update for it which will enable 1333Mhz cpus to be used in it ??

who is the MB made by ??
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September 14, 2007 5:38:40 PM

Thanks for the best wishes and the suggestion to check for BIOS updates. I'll do that.

I was hoping that someone might be running a CPU with a buss speed of 1333 on a motherboard with a system speed of 1066 and would be able to tell me that it will work fine or not.

I don't know enough about overclocking to understand whether the 1066 buss speed of the motherboard is something that is usually and easily changed or not. Nor do I understand whether there are stability or other problems with doing this that would justify getting a new CPU or motherboard instead.

So, please, if anyone has some information about this, I need your help in order to make up my mind whether to try this or go through the process of returning the CPU for another one, which in this case means waiting another week or so.

Thanks.
September 14, 2007 6:32:29 PM

as far as i have heard that due to the chipset limitation, there will be a luck factor in this. i mean that some motherboards, i.e D975XBX2, will work while others will not. i know this sounds weird and this was the only reason y intel first brought an updated bios on their website and then removed it after a week, i think. one thing u can do is to google about the version that supported 1333fsb cpus and then try to download that bios from somewhere else. hope i helped.
September 14, 2007 6:58:44 PM

Some new information...

I read through the BIOS information on the Intel.com site and several of the updates say they add 'Updated Processor Support' but they don't say anything more than that. No info on what processors or what kind of update to them.

Information from newegg.com site seems to indicate that this CPU/mb combo might be ok. The have one of their 'bundles' that includes a 1333hz CPU with a 1066hz motherboard. It's a different mb, though. Also, in one of the reviews on newegg.com for either the mb or the CPU, I can't remember which right now, one of the users says he's doing great with this combination.

So, I'm holding out hope that this combo would work but I don't want to get it assembled and find out it won't.

That's why I was hoping that someone would have already tried it and would know one way or the other.
September 14, 2007 7:00:24 PM

The front side bus is linked with the cpu clock... To get the 2.66 ghz of the E6750, it works like 8(CPU Multiplier) * 1333 (FSB) / 4 (Cycles) = 2.66.

If the north bridge bus speed does not support 333 and only 266 (1066/4) it will not work. Think of it as logarithmic bases? (That analogy makes sense to me)

If you are in the market for a new processor at $200, the E6420 is a good choice and will OC fine. It also has a multiplier of 8, while the E6600 has a multiplier of 9. Hope this makes things clearer...

In terms of OCing, all these processors have locked multipliers, so you have to raise the FSB speed... but to start, they have to both be able to operate at the same base.

Edit - note that it is the the north-bridge on the mobo that determines whether it can support it... Certain mobos which initially say they only support 1066 may in fact be able to support 1333 with a bios update. It all just depends on whether or not the north bridge will accept it. I also found this, last updated August 27, http://support.intel.com/support/motherboards/desktop/d...
It does not list the E6750 as a supported processor.
September 14, 2007 7:19:28 PM

Well, I guess I need to go get a different CPU that runs at 1066hz, then. Intel has responded to me about this issue as follows:

"Regarding your technical question, we regret to inform you that the Intel(R) Desktop Board D975XBX2 was designed to support processor front side bus speeds of up to 1066Mhz, therefore no support is provided for the new generation of Intel(R) processors with 1333Mhz FSB, not even with the latest BIOS version. "

I just wish things were more 'black and white'. They say it's not 'supported'. They didn't say 'it won't work'.
September 14, 2007 7:32:50 PM

There ultimately is no real benefit that can be seen from 1066 to 1333, the performance difference is marginal. The main thing is to get a good OC out of your processor and memory. As I mentioned earlier, the E6420 is a good choice for you since it also has an 8 multiplier... If you have DDR2-6400 RAM, you can get the E6420 up to 3.2 ghz easily... You should have no heat issues with that processor.
September 14, 2007 7:56:09 PM

Thanks for your help, jys84.

I've ordered the E6420 CPU and will return the E6750 when it arrives on Monday.

I also bought a "CPU COOLER ROSEWILL|RCX-Z5" and assuming that it fits in the case, I don't anticipate any cooling problems.

I would like to oc this rig but I've never done that before and will have to get some specific information about how to do it without actually blowing anything up.

Is there a quick primer on this that you could recommend? Hopefully, something that doesn't involve logarithmic bases, maybe? :) 
September 14, 2007 10:23:59 PM

The 975XBX2 will overclock to 333MHz (1333 MT/s) FSB easily, at this point the CPU would be running at stock speed....

Hell, my 975X board is currently running at 380MHz with an e6700.
September 14, 2007 10:48:42 PM

Yes, darkstar782, but the E6700 chip is a '1066' chip. The E6750 is an '1333' chip. Are you saying that doesn't matter?

What about this business of multipliers of 8 and multipliers of 9. Not to mention the logarithmic bases...

I've got a headache already and the stuff hasn't even arrived yet.
September 15, 2007 6:17:01 AM

man if u have ordered e6750 then y dont u give it a try rather than just returning it?
September 15, 2007 6:18:57 AM

Dude, because if it's used they might not take it back. And even if they did, I want to build the system once and do it right the first time. Not screw around with it over and over again.
September 15, 2007 7:52:23 AM

There's a chance that your main board doesn't support the 1333MHz FSB CPU ID so it won't even complete POST saying that you have used an incompatible CPU. Like, when you put a 1066MHz FSB on an older 945 generation chipset main board which does not have the new voltage regulator. Beside as the OP said, take the safe road.
September 16, 2007 10:40:23 AM

Worst case scenario is that the motherboard posts at 266*8 rather than 333*8.

I should probably have mentioned that my e6700 is pinmodded for a 1333MT/s FSB on the off chance that it is resulting in a higher bootstrap. At the moment I am running at 370*10.

All you then do, is overclock the board to 333MHz FSB, and there you have stock speed.

The motherboard may not recognise what the chip is, but it will work.

There will be no VRM or other power supply issues - this chip is still a Core 2.
September 16, 2007 6:42:10 PM

Facinating...

So, one of the routine things you can do in the BIOS as part of oc'ing a system is change the mb's system buss speed? Say from 1066 to 1333?

How do you 'pinmod' a CPU chip?

Isn't an E6700 chip designed to work at 1066 out of the box? The E6750 is designed to work at 1333 out of the box.

And, what is a VRM?
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