If AMD (AMD) shares were still trading below $10, as was the case in early December, markets would likely take the initial reviews provided for the company's Ryzen desktop CPUs in stride. But with shares closing close to $15 recently, the reviews were expected to make good on all of the hype surrounding the Ryzen chips, including their competitiveness relative to Intel's (INTC) high-end Core i7 CPUs. And they didn't quite do that.

As a result, AMD closed down 7% to $13.90 Thursday in response to the reviews and were down another 2.5% in pre-market trading on Friday. Shares are still up 23% on the year, and over 600% from their early-2016 lows.

In a nutshell, Ryzen reviews often show the two most powerful chips in the product line, the 1800X and 1700X, holding their own against more costly Intel CPUs in productivity and media-encoding benchmarks, but coming up short in gaming benchmarks. "Good, but not for gamers," reads the headline of a much-discussed Ars Technica review.

The review had the Ryzen 1800X ($499 MSRP) outpacing Intel's Core i7-6900K ($1,089-$1,109 "recommended price range") in the Cinebench 3D rendering benchmark, just as AMD promised. It also outperformed in video encoding and storage tests, albeit while moderately underperforming in tests involving the Geekbench and 3DMark benchmarks.

A bunch of non-gaming benchmarks run by AnandTech -- its CPU and GPU reviews are a must-read for those wanting wonky, stat-filled analysis -- yielded a similar mixed bag. In many rendering, encoding, productivity and CPU system tests, the 1800X matched or beat the 6900K, which is based on Intel's older Broadwell architecture (launched in 2014). But AnandTech also found a "few edge cases" -- for example, certain compression and image-processing tests -- where Intel had a sizable lead.

AnandTech's explanation for this was that Intel's superior R&D resources make it easier for the company to address these "edge cases" through various optimizations. But with Intel paring back its PC R&D spend to devote resources to other areas, it's not a given that this will continue.

Either way, it's the gaming benchmarks that have raised the most eyebrows. When playing Ashes of the Singularity and Hitman at 1080p resolution, Ars found the 6900K often had a performance edge (as measured in both average and 99th percentile frames per second) north of 20%. Smaller leads were posted for Rise of the Tomb Raider and GTA V.

Perhaps more importantly, the gaming benchmarks also found the 1800X underperforming Intel's recently-launched Core i7-7700K CPU, which is based on the newer Kaby Lake architecture and sells for about $350. On the flip side, the 1800X easily outperformed the 7700K in most non-gaming tests.

AMD's 1800X has 8 cores with a base clock speed of 3.6GHz (4GHz turbo), while the 7700K has 4 cores sporting a base clock speed of 4.2GHz (4.5Ghz Turbo). Ars' takeaway: Most games still aren't able to make full use of 8 CPU cores, and thus a 4-core CPU running at higher clock speeds will for now provide gamers with more bang for the buck.

Many of PCWorld's gaming tests turned up results not too different from Ars Technica's. But the site also found that the 1800X significantly narrowed the 6900K and 7700K's performance leads when more demanding gaming settings, such as a 2560x1600 resolution or a high-quality preset, were applied.

This is pretty important for a chip that -- if bought for a gaming system -- is more likely to be used by hardcore gamers as opposed to casual gamers. "You don't, after all, buy a $500 CPU and $500 GPU to run at 1920x1080 at 'normal' settings," PCWorld's Gordon Mah Ung points out. AMD, for its part, claims Intel's gaming performance edge is completely eliminated at a 4K resolution, which more and more hardcore gamers are using. Some of AMD's Ryzen demos seem to back this up.

Regardless, as far as AMD's sales go, the most important takeaway from the reviews may be that they show Ryzen to be a compelling alternative for a large percentage of consumer and corporate PC buyers wanting mid-range or high-end performance, in a way that AMD's offerings haven't been for years. "AMD's Ryzen is arguably the most disruptive CPU we've seen in a long time for those who need more cores," writes Ung in his conclusion.

Likewise, Ars' Mark Walton suggests the 1800X offers a compelling value proposition for "content creators, budget-conscious streamers, and workstation users," even as he recommends gamers buy Intel's 7700K. He also notes AMD might be able to improve its gaming position by releasing better drivers, or by launching 4-core Ryzen chips featuring high clock speeds.

Intel, it should be pointed out, isn't standing still. The company appears to be cutting its high-end prices -- online retailer Micro Center now sells the 6900K for $1,000, and the 7700K for $300. And new high-end CPUs based on Intel's Skylake architecture (launched in 2015) are due this summer, including possibly a 12-core chip.

But while Intel tries to counter AMD's high-end challenge, AMD will be moving downmarket: Ryzen chips with integrated GPUs based on AMD's new Vega architecture are expected for the notebook and "mainstream" desktop markets later this year. Looking out to 2019, AMD plans to launch Ryzen chips based on its next-gen Zen+ CPU core architecture -- a revamped version of the Zen architecture used by Ryzen -- and relying on a cutting-edge 7-nanometer manufacturing process.

The PC CPU wars are indeed far more interesting than they have been in years, thanks both to AMD's latest efforts and Intel's R&D cuts. The first Ryzen reviews drive this home, even if they didn't live up to the most optimistic expectations.

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