CPU Clock Speeds

[Vek1313]

How much of a difference in performance does it make for CPUs. Something such as 4 GHz as the i7 4790k and 3.5 i5 4690k? I don't want any replies due to for gaming just get the i5, I know that and that isn't the question. I just want to know how much performance is affected by clock speed.

[runit3]

Performance in what exactly? It entirely depends on the application(s)

[AlwaysFSX]

A couple percent at most. You could drop it to 2 GHz and still get most of the performance, CPUs aren't what makes or breaks performance for the most part.

[Vek1313]

Performance in what exactly? It entirely depends on the application(s)

Well I will be doing rendering a decent amount so I know the i7 is better than the i5 in that but I want to know how clock speed affects performance?

[Vek1313]

A couple percent at most. You could drop it to 2 GHz and still get most of the performance, CPUs aren't what makes or breaks performance for the most part.

Ok because I was making my decision between the i7 4790k and the Xeon E3 1231 and I didn't know if it would be beneficial to get the i7 just because of the higher clock speed.

[FruitBasketSilex]

Honestly, clock speed only matters within the same architecture. You can only say a pentium at 2ghz will perform half as well as an i7 at 4ghz.

An fx processor at 5ghz doesn't equal an i7 at 5ghz.

[AlwaysFSX]

Ok because I was making my decision between the i7 4790k and the Xeon E3 1231 and I didn't know if it would be beneficial to get the i7 just because of the higher clock speed.

Not really, you wouldn't really notice a different unless the i7 was clocked way above the Xeon.

 

Honestly, clock speed only matters within the same architecture. You can only say a pentium at 2ghz will perform half as well as an i7 at 4ghz.

An fx processor at 5ghz doesn't equal an i7 at 5ghz.

Okay.. this post means what exactly? Because the OP specified.

[Vek1313]

Honestly, clock speed only matters within the same architecture. You can only say a pentium at 2ghz will perform half as well as an i7 at 4ghz.

An fx processor at 5ghz doesn't equal an i7 at 5ghz.

So how much performance difference between the Xeon E3 1231 and the i7 4790k?

[WoodenMarker]

Well I will be doing rendering a decent amount so I know the i7 is better than the i5 in that but I want to know how clock speed affects performance?

It depends on what's being rendered and the program being used. 

So how much performance difference between the Xeon E3 1231 and the i7 4790k?

The only difference is in the clock speed and how performance pans out will depend on the scenario.

[Vek1313]

It depends on what's being rendered and the program being used. 

The only difference is in the clock speed and how performance pans out will depend on the scenario.

Videos for youtube will be rendered and using Sony Vegas 13.

[WoodenMarker]

Videos for youtube will be rendered and using Sony Vegas 13.

Vegas renders can benefit quite a bit from gpu acceleration and the cpu shouldn't make that much of a difference. 

[runit3]

Well I will be doing rendering a decent amount so I know the i7 is better than the i5 in that but I want to know how clock speed affects performance?

I have little experience with rendering (3D), however a lot with encoding videos. Assuming the software can maximize all cores/threads clock for clock an i5 should perform ~17% worse than an i7 (Intel claims up to 30% improvement with HT, but I have yet to see benchmarks confirming this). Again, this entirely depends on your application's ability to utilize hyperthreading. If it cannot utilize hyperthreading at all they will perform exactly equally at the same clocks. The only difference between an i5 and an i7 is the HT on the i7 and minor differences in base clock.

 

The OP question is a little flawed as you're trying to correlate clock speed on top of the inherent differences in HT vs. non-HT. An i5 is an i7, just without HT, if they have equal clocks they are equal. The clock scaling between the two will follow a completely linear model +/- the difference in applications that can/cannot utilize HT.

 

So, I guess to answer the OP question directly, a 3.5GHz i5 will perform a given task 12.5% slower + the difference in HT, compared to a 4GHz clocked i7. If you were rendering something that took the i7 10 seconds the i5 could do it in roughly 11.25s+ ~1.7s for no HT, for a total of ~12.95s, 2.95s slower than the i7.

 

*edit* this is a grossly simplistic answer, the results will again completely depend on the software being used. If you have a specific application in mind it would be best to go look up benchmarks, most will include both i5's and i7's.

[sgloux3470]

How much of a difference in performance does it make for CPUs. Something such as 4 GHz as the i7 4790k and 3.5 i5 4690k? I don't want any replies due to for gaming just get the i5, I know that and that isn't the question. I just want to know how much performance is affected by clock speed.

 

 

Well like every question: it depends.

 

If you're CPU bottlenecked?  Clock speed can make a huge difference.  

 

 

 

You can see that as the clockspeed decreases, average framerate decreases with it.

 

If you're not CPU bottlenecked, then it doesn't matter.

 

 

You can see here that adjusting clockspeed has a much smaller effect on average framerate.

 

 

Outside of gaming is a bit different, as performance will almost always scale with clockspeed.  How much depends on the workload, memory speed and a host of CPU/DRAM configuration settings.  To keep it simple, 4 GHz is about 15% faster than 3.5 GHz.  Which means a 5 minute render time will become 4.25 minutes in an ideal world. (In reality, it's often less than that.)

 

 

That's before you add in hyperthreading, which either does absolutely fuck all or offers ~30% more performance depending on the workload.  

 

 

In general, the difference is often quite small.  The only time the extra money for an i7 makes sense is if you do enough of a task that benefits (i.e video rendering benefits significantly from hyperthreading) wherein all those seconds shaved off will add up significantly.  Personally, I think at the point where someone is considering an i7, they should be considering the X99 platform instead.  The only person who I feel the i7 really works nicely for is the youtuber or streamer who does a lot of production work but isn't doing it professionally wherein the X99 platform is the obvious choice.  

[Vek1313]

Well like every question: it depends.

 

If you're CPU bottlenecked?  Clock speed can make a huge difference.  

 

 

 

You can see that as the clockspeed decreases, average framerate decreases with it.

 

If you're not CPU bottlenecked, then it doesn't matter.

 

 

You can see here that adjusting clockspeed has a much smaller effect on average framerate.

 

 

Outside of gaming is a bit different, as performance will almost always scale with clockspeed.  How much depends on the workload, memory speed and a host of CPU/DRAM configuration settings.  To keep it simple, 4 GHz is about 15% faster than 3.5 GHz.  Which means a 5 minute render time will become 4.25 minutes in an ideal world. (In reality, it's often less than that.)

 

 

That's before you add in hyperthreading, which either does absolutely fuck all or offers ~30% more performance depending on the workload.  

 

 

In general, the difference is often quite small.  The only time the extra money for an i7 makes sense is if you do enough of a task that benefits (i.e video rendering benefits significantly from hyperthreading) wherein all those seconds shaved off will add up significantly.  Personally, I think at the point where someone is considering an i7, they should be considering the X99 platform instead.  The only person who I feel the i7 really works nicely for is the youtuber or streamer who does a lot of production work but isn't doing it professionally wherein the X99 platform is the obvious choice.

Yeah but the X99 is a bit out of my budget and I wouldn't be able to upgrade for another year...

[FruitBasketSilex]

Not really, you wouldn't really notice a different unless the i7 was clocked way above the Xeon.

Okay.. this post means what exactly? Because the OP specified.

The OP asked how clock speed mattered, I was adding to others, that it changes across architectures.