- Joined
- Nov 1, 2012
- Messages
- 1,007
- Motherboard
- GA-Z77X-UP5 TH
- CPU
- i7-3770K
- Graphics
- HD4000 / GTX 1050 Ti
- Mac
- Classic Mac
- Mobile Phone
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:
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.
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!
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:
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.
- A 1-core ratio of 39x.
- A 2-core ratio of 38x.
- 3-core and 4-core ratios of 37x.
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!