Need a Straight OC Spec

In regards to your CPU, the way to OC is to increase your multi, as most mobos don't have the option to raise the Bclk (A.K.A. FSB), or if the mobo does have the option, increasing the bclk causes instability.

The difficulty is that when people mention doing an OC on this CPU, they often leave out whether the 4.5 is with or without turbo. The i5-2500K has a turbo boost function that automatically accelerates the CPU frequency, based on the settings you adjust. That said, check out this site, but note that the mobo used is different; however, the "take-home" info is learning what the features do.

http://www.bit-tech.net/hardware/cpus/2011/01/07/how-to...

Clearing CMOS will revert the BIOS back to the settings the mobo left the factory, meaning your OC settings as well as the system date/time will all be reset.

Loading default values will revert your OC settings back to stock settings, without changing the system time/date.

I do not have a Sandy Bridge processor but the concept is the same. If you want a quick OC to game with I would recommend finding a stable OC using just the multiplier and the voltage. Save that and play games with it, then if you want to explore further into the addicting world of OC then you can always fall back to that when you are done experimenting and don't have a stable OC yet. That is pretty much the idea you had with your 4.5GHz plateau but like I said I would recommend getting there the easy way and saving that first, then do more exploring.

On the topic of Multi vs. Bus speed, like I said it is much easier to OC with just the multi. The problem with the bus speed is that it effect many things on your mobo so there are many things to keep track of and more components influencing how far you can push the bus speed before something fails.

That being said the benefit of OC with the bus speed is the same as the worries. Everything gets OCed. So generally a system OCed with the bus will bench higher than a system OCed with just the multi.

So the choice is yours but I will stick with my original advice. OC now with the multi and if you want to dive in head first do the OC with the bus speed later.



There are also 2 stickies in the OC forum here at toms that are specifically for sandy bridge processors. I would start there to answer most of your questions.

I read, but I think I missed the answer. So,,,,, Am I supposed to turn the turbo boost off?

The basic way to OC the i5-2500k is, as J2j773 mentioned, by keeping your bclk at default and increasing the CPU multiplier. Once you find a multiplier that doesn't boot into Windows, you've reached your first fail point.

From this fail point, you've got two options:

1. Step back the multi by 1 until Windows loads; or
2. Increase voltage to the CPU.

Either way, once Windows loads, you need to test for stability. The recommended software to do this is either Prime95 or IntelBurn Test.

The link I posted earlier describes some features/terminology you may encounter on your journey to OC. My point about turbo and non-turbo is that way too many i5-2500K owners ask about how to OC to 4.5 GHz, but never specify if they want 4.5 GHz in turbo speed or non-turbo speed.

The article I linked assumes that you're goal is to get to 4.5GHz with turbo boost enabled (for that extra umph when you need it) and 3.3 GHz w/o turbo boost (for the day-to-day operations, such as web browsing, checking e-mails, and the like).

Edit: Let's also assume that you can simply mimic the settings from the article I posted. From here, you can still OC higher by raising your multi, but there will come a point where you can't; shouldn't, rather, volt any higher on the CPU. However, for the sake of discussion, let's assume that the settings posted in the article were the absolute highest OC w/o changing the bclk. Now, if you wanted to OC further, you would have to raise the bclk, but with that, you'd be changing the DRAM frequency too. This is where the second fail point would be, and where the advanced OC begins.

All right, all right. I set everything back to default, took it to 4.5 (like I said, that's all I want to start with), and ran Prime95. Failed first time asap so I pushed up the vcore up one notch. Ended up doing it twice and now I've been stable at 1.37 for 20 minutes. Obviously I'm going to need it stable for much longer than that, but a start.

Question, when I'm running Prime, am I looking for it to make it hours (say 12) without a worker stopping/failing? If I can make it around then, can I claim I'm stable (for the most part)?

Also, what max temp do you think I should keep it under at full load?. I'm assuming around 70c no higher than 80c), but I hear a lot of different things. You seem to know you $#!T, so I figured I'd ask while your still answering. P.S. MUCH thanks for still answering.   I think you seem to answer all my questions on here.

Best answer selected by Hidegski.

Looks like things are working. I got up to a little over 2 hours on P95 before blue screen. I'll play some more and hopefully get fully stable. Mucho thanks again.