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Core i7-3770K is slower than i7-3770

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For what it's worth, I've gotten about 14,900 on a non-OC 3770k Gigabyte z77 ud5h board.
 
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It does indeed look like 40 on a non-K, I stand corrected =).

In regards to the bios, Gigabyte is the sneakiest when it comes to all-core overclocking. Unlike Asus and MSI, GA doesn't even have a bios setting, it happens transparently. I've personally seen it several times, and there are many articles on the subject. GA was the first to start doing this, and did not mention it. It was only after their boards mysteriously started beating all competition that people investigated and found out. Since then most major MB makers have followed suit, but GA is the only one (to my knowledge) that still does it transparently.

In light of that, I still think it's probably a mistake in the bios, but maybe not. Maybe they wanted it to test well with the cheaper CPU.

I have no idea why you can get to 40. Intel claims it's a hard wired limitation, but maybe in fact the hardware is still there and they removed or recoded the standard address. Maybe Gigabyte found it and is being sneaky again =).

In any event, if you have the time/inclination, would be cool to see if it will actually do 43...

Would also be interesting if it will use multiple bins if all set above 39 (i.e. at default it's driving them all at 39 regardless of load, if you set say 42/41/40 would it still just drive them at 42, or would you see 40 with all-core load...).
 

DBP

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For what it's worth, I've gotten about 14,900 on a non-OC 3770k Gigabyte z77 ud5h board.
Yeah, it's worth something but I'm not sure how much. RAM/etc comes into play as well when comparing different machines.

In any event, if you have the time/inclination, would be cool to see if it will actually do 43...
Yeah, but that would imply that (a) I had faith in the stock Intel cooler, and (b) I had time to do lots of tweaking and rebooting this machine (it's in an office where I'm using it in actively doing real work).
We'll see. :)
 
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Well, the title tells part of the story, anyway. The i7-3770 at its stock configuration is faster than a non-overclocked i7-3770K. Don't believe me? Read on.

The i7-3770 is described by Intel as a 3.4 GHz CPU (with turbo to 3.9 GHz) while the i7-3770K is 3.5 GHz (again with turbo to 3.9). So it's natural to assume that the 3770K is faster. I've seen people configure a system with a 3770K even though they're not going to overclock it just for that extra 3% of CPU speed. In fact most of the time it's 5% slower! How's that? It's all about the turbo.

Turbo Ratios in the i7-3770K:
Overclockers quickly become familiar with the Turbo ratios you can set in the BIOS. By default the 3770K has:
  • A 1-core ratio of 39x.
  • A 2-core ratio of 38x.
  • 3-core and 4-core ratios of 37x.
With the default base clock of 100 MHz, this means that if only one core is active the CPU will be clocked at 39x 100 == 3.9 GHz. But that's only if 3 cores are idle. If a second core is active the clock reduces to 3.8 GHz, and so on.

However, it's very rare for OS X to turn off cores. Even if you've got one process chewing 100% CPU (visible in Activity Monitor) it's common to see the load spread across the cores (visible in Activity Monitor's CPU History window for example). Most of the time under load an i7-3770K is a 3.7 GHz CPU.
Intel don't publish the default 1/2/3/4-core ratios, just saying "up to 3.9 GHz". And they say the same for the i7-3770.

My first i7 CustoMac was an i7-3770K (on a GA-Z77X-UP5 TH motherboard) and after overclocking it to 4.4 GHz (mainly by increasing the turbo ratios to 44) I was familiar with the way turbo worked in the 3770K. But when I started working with an i7-3770 system (on a GA-Z77-D3H motherboard) I quickly noticed something different.​

On the i7-3770 all four turbo settings are 39. So with all four cores "active" (as OS X tends to do) an i7-3770 is a 3.9 GHz CPU.
Now it's possible that the motherboard BIOS is bumping up the turbo settings from the chip's own default (after all, it might make the board seem to benchmark as faster than others?) but if that was the case why wouldn't the boards also do it when using i7-3770K CPUs?


I've confirmed this with HWMonitor, and by observations of increased Geekbench Integer and Floating Point results with the non-K chip. On the i7-3770 the CPU runs at 3.9 GHz. On a non-overclocked i7-3770K it runs at 3.7 GHz (very very occasionally jumping up to 3.9 GHz for single-threaded workloads).

Of course, the K processor can be overclocked further than the non-K, so once you start overclocking any slight advantage the non-K chip had quickly disappears. Also note that raw CPU speed is not the only thing affecting the performance of your computer, so "5%-slower" CPU does not mean your computer would be 5% slower. RAM, I/O, GPU, networking, all these things come into play.

The bottom line is that the difference is very minor, but if you're considering what chip to purchase for a new build and you're not intending to overclock, don't assume that the more-expensive 3770K will be better!​


Do you think I missed anything? Have you observed situations where the K is actually faster than the non-K when you weren't overclocking? And yes, I know it's actually possible to change the turbo ratios of the non-K CPU!
DBP, thanks for this read. It was a very good read. I will probably use the i7-3770 instead for the next build. :)
 

DBP

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On the 3770K machines I've used this doesn't go above 3700 MHz without overclocking.

I'm enjoying this thread. Thanks for doing this. My 3770k shows up as 3.9 MHz in HWMonitor when under a heavy load (not overclocked). It seems weird that yours shows up as 3.7.
 

DBP

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My 3770k shows up as 3.9 MHz in HWMonitor when under a heavy load (not overclocked). It seems weird that yours shows up as 3.7.
Curious. This may be related to the system definition you're using. Which is it?
And when you say "a heavy load", how many cores were active? (for example looking in Activity Monitor's Floating CPU Window) Four of them or only one?

If all cores were busy then I would be suspecting that your BIOS might be automatically overclocking to 39,39,39,39 instead of the default 39,38,37,37 (just as this D3H motherboard does with the 3770). If you changed the settings from Auto to these specific numbers do you get the same behaviour on your 3770K?
To be complete I'll redo that specific test next week when I'm back at that 3770 machine.
 
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I will sure check out my bios when I get back on that machine. I haven't changed any of the turbo settings so they should be the default. When I run a blend mode in Prime 95, I see HWMonitor showing 3.9. I haven't checked Activity Monitor but will do that for you...even though Prime95 should be doing 8 threads.
 
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Yes, my processor is at default settings in BIOS.

CPU_BIOS.jpg

Here is HWMonitor showing 3.9 MHz.

HWMonitor.jpg

Here is the CPU window of Activity Monitor. This part does not make sense to me as I expected Prime95 to have 8 threads and nearly 100% of the processor...not 798.1% of the processor and 11 threads.

activitymonitor.jpg
 
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