Back in late 2013, Intel (NASDAQ:INTC) gave its low-end PC chip product line a long-overdue refresh with the Bay Trail platform. Bay Trail brought in a brand-new CPU core, called Silvermont, which delivered a huge boost in general-purpose performance over the prior-generation core known as Saltwell. Intel also included a significantly more robust graphics and media engine with Bay Trail over the older Cedar Trail platform.

Here in mid-2015, about a year and a half since the Bay Trail-based PC chips hit the market, Intel's follow-on platform, codenamed Braswell, is starting to hit the market. There aren't a lot of Braswell-based notebooks out in the market today from what I can tell, but you can buy Braswell-based desktop processors and motherboards today.

French hardware review site Hardware.fr tested Intel's Pentium N3700 and N3150 Braswell-based processors. Is this chip a winner, or is it a dud? Let's take a closer look.

Disappointing CPU, but good graphics improvement
Hardware.fr showed performance-per-watt numbers for the Bay Trail chips as well as the Braswell chips in a test known as Luxmark, which isolates CPU and graphics performance and also tests both the CPU and graphics running in tandem.

Braswell delivers a big boost in graphics performance per watt in the Luxmark graphics-only test. While the older Bay Trail-based Celeron J1900 and Pentium J2900 deliver approximately 2.11 units of performance per watt in graphics, the Braswell Celeron N3150 delivers 5.75 units of performance per watt, while the N3700 delivers 5.72.

But in terms of CPU performance per watt, Hardware.fr reports a regression in moving from Bay Trail to Braswell. The Bay Trail-based J1900 and J2900 deliver 7.13 and 7.09 units of performance per watt, while the Braswell-based N3150 and N3700 only deliver 6.15 and 6.65 units of performance per watt.

These measurements indicate that something went wrong with the Airmont CPU core inside Braswell. The architecture of Airmont is probably very similar (if not identical) to Silvermont, and it was moved to a more efficient manufacturing process, so seeing a regression in performance per watt at similar performance levels is not a good sign.

Intel needs a new revision of Braswell as a bridge to Apollo Lake
The follow-on platform to Braswell is known as Apollo Lake, and it should be built on the same 14-nanometer manufacturing technology as Braswell is. However, it should also bring an entirely new architecture. This enhancement is expected to include a brand-new CPU core, codenamed Goldmont, a new graphics and media architecture, and a much more robust memory interface to feed the system-on-a-chip.

Apollo Lake isn't expected to ship until around the May 2016 timeframe. I would hope to see a revision of Braswell between then and now to try to improve the performance per watt of the CPU on Braswell, although it may be a design issue that's too complex to fix with a new chip revision.

Intel needs to do better next time
The graphics boost in terms of raw performance and performance per watt is certainly welcome, as it allows low-cost Intel PC platforms to be better at handling media-rich applications such as video playback and light 3D gaming. However, Intel really needs to improve the CPU performance of its platforms as well.

Although the competition in the PC space isn't as fierce as it is in the Android tablet and phone space, Intel uses the same fundamental low-power CPU architectures across many different segments. CPU performance is still an important vector along which Intel needs to innovate, and as an investor, I hope future Atom processors take improving CPU performance and performance per watt more seriously.

Ashraf Eassa owns shares of Intel. The Motley Fool recommends Intel. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.