Is a 3rd Generation Intel Core i-3 better than 2nd Generation Core i-7

That is normal for 3 main reasons:

1. the benchamrks score depends on the ram installed, whether it is in dual channel mode or not, so a core i5 with faster ram may perform faster.

2. heat sink and cooling, those processors are usually coupled with heat sink and fans that can only dissipate heat generated by 15 watt of power, which is the required by Intel, however, to achive higher turbo boost speeds, the processor needs to use more power than 15w, so it depends on the specific laptop and how much heat it can dissipate above the required 15 watts.

3. different manufacturers may limit the power draw when the processor tries to use more than 15 watts, to avoid possibly overheating the laptop.

The only thing you can do is to check that your laptop is cooling properly and not limited due to over heating.

If the processor is limited due to OEM, you can complain to them, in some cases they may relax limitation by a software update to the BIOS.

Both the i7-4790K and the i7-6700K have very similar profiles, both have:

• a base clock of 4GHz
• 4 Cores / 8 Threads
• 8MB Cache
• Support for SSE4.1/4.2, AVX 2.0 Instruction Set Extensions

However, there are also slight differences in:

• the system bus architecture: DMI3 @ 8GT/S (i7-6700k) vs. DMI2 @ 5 GT/s (i7-4790k)
• Boostclock: 4.2 GHz (i7-6700k) vs 4.4 GHz(i7-4790k)
• supported memory type: DDR4 (i7-6700k) vs. DDR3 (i7-4790k)
• memory bandwidth: 34.1 GB/s (i7-6700k) vs. 25.6 GB/s (i7-4790k)
• max. memory size: 64GB (i7-6700k) vs. 32GB (i7-4790k)
• integrated GPU: Intel HD 530, DirectX 12 (i7-6700k) vs. HD 4600, DirectX 11.2 (i7-4790k)

That being said, the performance difference one can expect between those CPUs is rather low. Though both have certain advantages. The features that will make the biggest difference between those CPUs are the considerably faster memory bandwidth of the i7-6700k vs the higher boost clock of the i7-4790k. So in practice, one can expect the i7-6700k to outperform the i7-4790k where memory bandwidth is crucial, whereas the i7-4790K will have slight advantages in applications requiring high single core compute performance - single core because that is the scenario where the CPUs will reach their highest boost clock.

Now to your questions:

1. Why is the benchmark slower?

The benchmark is slower because it seems to take advantage of the i7-4790k's higher boost clock rather than the i7-6700k's higher memory bandwidth.

2. Is 6th-gen actually slower?

As I explained above, this totally depends on the application. If you look at these results, you'll see the i7-4790k outperform the i7-6700k in some applications, where it's the other way around in other applications. But the most important observation you should take away from those results is:

In practice, there is not much of a difference in speed unless you're actually in need of very high memory bandwidth and overall memory size. For most homeusers, 32GB of RAM will likely be enough though.

3. Why would someone choose 6th-gen if 4th-gen is faster and cheaper?

Someone should definitely get the i7-6700k if he needs more than 32GB of RAM or is using applications relying heavily on memory bandwidth or wants certain features that are available only on newer mainboards.

If those advantages of the i7-6700k are not of use to you and the i7-4790k is considerably cheaper, you just might want to buy the i7-4790k, you will not notice a difference.

There is one more thing to consider, if you're into overclocking. The i7-4790k draws its advantages over the i7-6700k mainly from the higher boost clock. Rumors say that Intel has improved the thermal compound between die and heatspreader of newer CPUs. If this actually results in better heat dissipation for the i7-6700k, you might achieve higher overclocking rates with the newer CPU, causing the i7-4790K to fall behind the i7-6700k in its most important advantage - the higher boost clock. Still, the differences between both CPUs will be very small to not humanly noticeable.