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BCLK and disabling cores questions

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a b à CPUs
January 25, 2012 5:36:09 PM

Hi, I have my Core i5 2500k stable at 4.5Ghz, which is good enough for me considering I only have a single GPU, but I just want to see how far I can push it. I am running a Corsair H60 cooerl and an ASROCK Extreme3 Gen3 motherboard.

I have heard that tuning the BCLK on SB chips can hurt the CPU and board, but I know some people have done it with success and have not had issues. Would something like a 3-5mhz tuning of the BCLK hurt the chip?

Second question about disabling cores. I wanted to see how far I could push the overclock with just 1-2 cores running and set my machine to 4.8Ghz and went to boot but it would not even post and I had to clear the CMOS. How can I disable cores and still boot? Am I missing something? It seemed pretty straight forward, but obviously it isn't working.
a b à CPUs
January 25, 2012 6:16:13 PM

For the base clock, that's tied into a lot of sub systems. I don't know exactly what the effect would be, but generally people are worried about how it affects the PCIe frequency. Well, on my PC I've had my PCIe up from 100 to 130. I run mine daily at 110. There were some issues with it up at 120-130 but nothing that isn't fixed by reducing it. I'd say you could probably get 5-10mhz out of the base clock, if the PCIe is the limiting factor.

I'm also not sure about disabling cores. In theory it should be straight forward. You should try doing it again at 4.5ghz just to see if it works.
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a b à CPUs
January 25, 2012 6:55:46 PM

wolfram23 said:
For the base clock, that's tied into a lot of sub systems. I don't know exactly what the effect would be, but generally people are worried about how it affects the PCIe frequency. Well, on my PC I've had my PCIe up from 100 to 130. I run mine daily at 110. There were some issues with it up at 120-130 but nothing that isn't fixed by reducing it. I'd say you could probably get 5-10mhz out of the base clock, if the PCIe is the limiting factor.

I'm also not sure about disabling cores. In theory it should be straight forward. You should try doing it again at 4.5ghz just to see if it works.

Okay, but I have heard that BCLK tuning on SB systems can hurt them. Is this true?

I will try disabling cores at 4.5Ghz.
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a b à CPUs
January 25, 2012 6:56:11 PM

wolfram23 said:
For the base clock, that's tied into a lot of sub systems. I don't know exactly what the effect would be, but generally people are worried about how it affects the PCIe frequency. Well, on my PC I've had my PCIe up from 100 to 130. I run mine daily at 110. There were some issues with it up at 120-130 but nothing that isn't fixed by reducing it. I'd say you could probably get 5-10mhz out of the base clock, if the PCIe is the limiting factor.

I'm also not sure about disabling cores. In theory it should be straight forward. You should try doing it again at 4.5ghz just to see if it works.

What exactly does PCI-E frequency do?
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a c 151 à CPUs
January 25, 2012 10:10:48 PM

pcie frequency is the pcie bus speed; its how pcie device communicate with the cpu & ram. Stock is 100Mhz. How far you can 'tune' it often depends on what devices are on the bus.

Bclk is the internal Intel Base Clock and potentially effects everything. If you change it 10% you might change all the other clocks too like cpu speed (bclk*multiplier), quickpath (QPI), memory, and PCIe though most motherboards now include bios settings to individually control those speeds.

As for overclocking the bclk, exept for the k series chips, the bclk is all many people get to adjust. Overclocking in itself can cause damage. I dont think overclocking the bclk would hurt and worse. I've seen a few system hit 220mhz bclk but most stop around 200.

edit - to disable cores there is an option in the bios thats something like enable multi-cores. disabling it disables the extra cores in the cpu.
Windows also has a set number of cores feature that you can set in the win.ini file.
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a b à CPUs
January 25, 2012 11:42:47 PM

Thank you. I will try to adjust my BCLK a little then. I want to just see if I can get a few hundred more Mhz out of the CPU by using the BCLK.
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a b à CPUs
January 26, 2012 12:09:16 AM

Well the one difference between SB and prior Intel chips is that the PCIe is tied directly to the base clock as opposed to being on it's own clock. That's why SB chips are so limited in OCing if they aren't unlocked. It's pretty sad, I mean my i5 750 is at 200 base clock, 110 PCIe, and only 20x multiplier on the CPU for 4ghz. My QPI is also super freaking fast at 7.4ghz lol.
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a b à CPUs
January 26, 2012 12:14:25 AM

Okay, so upping the BCLK didn't play nice. Haha. 100Mhz BCLK and 46 multiplier didn't work, so now I am going to try 97.9 - 98 BCLK and a 47 multiplier for 4.6Ghz. Wish me luck!
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a b à CPUs
January 26, 2012 12:20:49 AM

By the way, setting the BCLK down to 98Mhz shouldn't cause instability or long term damage, right?
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a b à CPUs
January 26, 2012 1:06:43 AM

It should be pretty much the same as increasing it as far as stability goes. As far as damage goes, I don't see raising or lowering it causing any harm besides some hard reboots.
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a b à CPUs
January 26, 2012 1:25:52 AM

wolfram23 said:
It should be pretty much the same as increasing it as far as stability goes. As far as damage goes, I don't see raising or lowering it causing any harm besides some hard reboots.

Okay! Sweet! Thanks! I have heard some rumors about it causing damage to the CPU. I have been running 4.6Ghz for about 1 hour now. 98 x 47.
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a b à CPUs
January 26, 2012 1:52:41 PM

At a 98 BCLK and a 47 multiplier, one core ended at 4 hours into the run but all the others were stable all the way through. Kinda sucks. Really waned that 4.6Ghz. Oh well, 4.5Ghz is good enough for me and my single GTX 460. :lol: 

Thanks for the help guys!
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a b à CPUs
January 26, 2012 1:53:21 PM

Acutally, I have one more question. What does QPI do?
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a b à CPUs
January 26, 2012 4:34:51 PM

Quick Path Interconnect. It's basically how all the components talk to each other. Theoretically you want it as fast as possible.
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a b à CPUs
January 26, 2012 4:36:12 PM

Oh. I believe that is like AMD's Hyper-Link speed, correct? How do I find out what mine is at?
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a b à CPUs
January 26, 2012 4:42:02 PM

Yeah pretty much.

Not sure, honestly. As far as I know it's still a multiple of the base clock like my 1156 and the 1366 chipsets. Default for me I believe is 34x multiplier. But with SB they took out a lot of that fiddling room as you already found out with the base clock issue.

I kind of don't like the P67/Z68 chipsets because of this. The CPUs are fantastic but the motherboards are lacking features. My QPI is now 200x34 lol.
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a b à CPUs
January 26, 2012 4:44:37 PM

Dang! Well, I am going to pick a best answer now. Thanks for the help!
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a b à CPUs
January 26, 2012 4:45:12 PM

Best answer selected by HostileDonut.
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a b à CPUs
January 26, 2012 4:51:28 PM

This topic has been closed by Mousemonkey
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