Intel Core i5 7640X processor review

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Final Words & Conclusion

Right, so this four cores and no hyper-threading proc still is a 112 Watt TDP processor. With the system at idle with a GeForce GTX 1080 installed / 8 GB memory / SSD and the X299 motherboard I hovered at roughly 45~50 Watts in IDLE. That's just lovely really. When we stressed the processor 100% run we ran roughly 90 Watts with this is a 4-core part so that TDP might just be a notch lower thean advertised. When we game we hover at ~245 Watts with the GeForce GTX 1080, but obviously that factor is dependent on the type of graphics card you use of course.

Bothersome 

Two things I find to be significantly bothersome, this launch is clouded by too many architectures and processors that really haven't been released. You can choose from 4 to 10 cores, which is fine. However Intel went big with announcement on 12, 14, 16 and even a 2000 USD 18-core part. The 12-core version should see the light next month, however the last three are nowhere to be found and I am starting to doubt that you'll see them anytime soon. The latest indication is October. Sure perhaps a review here and there to show off that Intel can do it. But retail availability? I don't know man.  So this all is cloudy and confusing really. But hey, this article hopefully cleared that up or at least made the topic more understandable. We have to discuss PCI-Express lanes. Here is the breakdown:

  • Kaby Lake-X quad core get 16 PCI-Express Lanes 3.0
  • Skylake-X six and eight core procs gets 28 PCI-Express Lanes 3.0
  • Skylake-X ten core procs gets 44 PCI-Express Lanes 3.0
So here we have the most expensive enthusiast class processor and X299 chipset series from Intel. A proper X299 mobo will be like ~300 USD, you spend ~250 USD on this four-core processor. So in the year 2017 you still cannot run two graphics cards at a full x16 PCI-Express lanes, as there are too few available lanes available. Actually Not even the 900 bucks you would spend on an 8-core part, as it will bog down towards two x8 links. Not a biggy I know, but really it is the year 2017 right? For M2 units the chipset offers plenty additional x3  Gen 3 lanes though.

Prices and value

So the breakdown goes like this:
  • $249: Core i5-7640X: 4C/4T, 4GHz-4.2GHz, 6MB cache, 16 PCIe lanes
  • $339: Core i7-7740X: 4C/8T, 4.3GHz-4.5GHz, 8MB cache, 16 PCIe lanes
  • $389: Core i7-7800X: 6C/12T, 3.5GHz-4GHz, 8.25MB cache, 28 PCIe lanes
  • $599: Core i7-7820X: 8C/16T, 4.3GHz-4.5GHz, 11MB cache, 28 PCIe lanes
  • $999: Core i9-7900X: 10C/20T, 4.3GHz-4.5GHz, 13.75MB cache, 44 PCIe lanes
Mind you that the prices in the EU are significantly higher, we spot this processor for € 259,- . So yeah, value for money wise a thing or two can be discussed alright. I made a plot, this is purely based on the Cinebench multi-threaded score mathed back to price versus relative multi-core performance:
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So in the above a mathematical plot, we take the CB score from CineBench 15. We normalize the value and basically plot how much money it takes to calculate the CB score. All processors are clocked at default frequencies, this plot would look different if you'd math in tweaked clock frequencies and thus get higher CB scores. Also you need to take the number of CPU cores into account (as in what number of CPU cores is relevant for you). But this is very simple math, have a peek at the chart (the higher a CPU is positioned the better).

So what are you seeing?:

  • An 8-core Core i7 5960X costs 79 cents per calculated CB. 
  • An 8-core Ryzen 7 1800X costs 25 cents per calculated CB. 
  • A 6-core Ryzen 5 1600 costs just 19 cents per calculated CB. 
  • A 10-core Core i9 7900X costs 42 cents per calculated CB.
  • A 4-core Core i5 7640X costs 36 cents per calculated CB. 

Value for money wise (Cinebench) shows that the entire Ryzen lineup offers the perf you get in return for your money (prices are based on Euro street prices or MSRP if a CPU is not available). Again this is a fairly subjective chart as it is based on just one test, but it does paint a certain picture. And please do not confuse the chart as to 'what is the better processor'. 

DDR4 Memory

Ever since Haswell-E was released along came DDR4 memory. With Kaby Lake-X DDR4 may be clocked a notch faster at 2,677 MHz. Honestly, if you pick up some nice 2,133 MHz DIMMs, at quad-channel it'll offer more than plentiful bandwidth. A 3,200 MHz kit for example is far more expensive and does offer better bandwidth but the performance increases in real-world usage will be hard to find. Unless you transcode videos over the processor a lot. DDR4 mostly was released for lower voltages and higher frequencies. 2,133 MHz CL 14 or CL 15 memory in combo with quad-channel will already get you to ~35 GB/sec. While impressive to observe for gaming you will not notice huge performance improvements with high memory bandwidth, but with content creation and video transcoding this kind of bandwidth certainly does make a difference. As always, my advice would be to go with lower clocked DDR4 memory with decent timings, but get more of it. Don't go for 8 GB, get four DIMMs and in total a minimum of 16 GB. 

Concluding

The €259 / 242 USD Intel Core i5-7640X works absolutely beautiful on X299. We had no real issues, good power consumption and nice game performance. More threaded utilization however is an issue as the proc simply has no SMT/HT capabilities and at just four cores you'd be really maxing things out. That's said, the Intel Core i5-7640X has absolutely no place being seated into a HEDT X299 platform. The motherboards simply are far too expensive for this type of processor as Intel charges an arm and a leg for the X299 chipset IC. You are way better off at Z170/Z270 or the B350/X370 Ryzen platform with a similar corresponding processor. However X299 might be a nice upgrade path down the line, you could start with a quad-core 7640X and perhaps in two years go with a more-core processor? That is something this platform can offer. However Intel has the tendency to release new processors always with a new chipset (to boost their sales). Hence two years from now, it might even be that the X299 and corresponding procs will be outdated by newer generation processors and chipsets. So you likely get to purchase it all over, again. Tweaking wise this is one of the better procs yet, temps remain at ~70 Degrees C with LCS overclocked to 5.1 GHz. 5.2 and higher is achievable, but at the cost of higher voltage, temps and power consumption. So that 5 GHz marker is certainly a sweet spot for this proc. The year 2017 is an exciting year in the processor arena. There are many things happening from the two primary brands, both keep each other in line and for the first time in a long time, both offer something very competitive. AMD Ryzen and its platform currently is extremely good. The X299 Core X platform (when all bugs are ironed out) can become exceptional. AMD however has the upper hand in value and energy efficiency and cores for your money. So more or less cores? In my opinion and again the age of the quad-core processor is an dying one. AMD sparked and ignited something in the processor and developer landscape with the release of affordable Ryzen 8-core parts. If you look for more value, I find the 6-core parts to be the better balance for what is realistic for today's gaming PCs relative to pricing and the overall PC experience. And then there was Kaby Lake-X with four cores, how come the Kaby Lake-X processors have pretty much the same specs as the Kaby Lake versions but have a higher TDP? They don't even have an IGP. Kinda weird right? Back to my thesis, currently I feel the six- and eight-core parts are probably the most interesting models if you are not that transcoding / ray-tracing / workstation type of user. Concluding, the benefits you'll gain overall simply are small compared to regular Kaby Lake. Overall though it is a fun little processor that does make up for a really nice gaming CPU with good tweakability. But as to why it is a separate SKU on X299, no clue.

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