Overall, U.S. and tech giants are still spending aggressively on their cloud infrastructures -- even if there's some choppiness here and there.

Here's a look at some of the things that were uncovered about cloud capex trends during earnings, as both major Internet/cloud service providers and their suppliers reported.

1. Google and Facebook Are Still Rapidly Growing Their Capex

Alphabet/Google's ( GOOGL) cash capital spending rose 49% annually in Q3 to $5.28 billion, something that CFO Ruth Porat attributed on the earnings call to both "data center construction projects in flight as well as ongoing expansion in [Google's] compute capacity." And though it's worth noting that real estate purchases made during the first half of 2018 are playing some role here, the consensus is for Alphabet's capex to rise 75% this year to $23 billion.

Facebook (FB) , for its part, used its Q3 call to lower its 2018 capex budget to a range of a $14 billion to $14.5 billion from a prior target of $15 billion. However, that still implies capex will more than double from a 2017 level of $6.7 billion. Moreover, Facebook forecast its capex will rise to a range of $18 billion to $20 billion next year.

Notably, when asked about Facebook's capex needs, CFO Dave Wehner suggested investments in server capacity used to support Facebook's feed and ad-ranking algorithms are playing a big role -- it wouldn't be surprising if, along the same lines, Google is spending heavily to support its search and ad-ranking algorithms. Wehner also noted Facebook is spending more to support Asian markets where it's still seeing healthy user growth.

2. Amazon's Capex Growth Is More Subdued

Amazon.com's (AMZN) purchases of property and equipment via capital leases, which is driven in large part by Amazon Web Services (AWS) and grew strongly during much of 2017, rose just 3% annually in Q3 to $2.33 billion. That follows a 14% drop in Q2.

On Amazon's call, CFO Brian Olsavsky reiterated his company's efforts to run its data centers more efficiently have much to do with the slowdown in data center capex growth. And while it's quite unlikely that Amazon's property/equipment lease growth will remain at such low levels, there's clearly a big contrast right now relative to Facebook and Google's capex growth.

3. Microsoft Is Somewhere In Between

Microsoft (MSFT) , Amazon's largest cloud infrastructure rival, reported that its capex rose nearly 60% annually to $4.3 billion. However, the company also forecast capex will be flat sequentially this quarter (that implies annual growth of around 30%), and reiterated capex growth will "moderate" in fiscal 2019 (ends in June 2019) from a fiscal 2018 rate of slightly over 30%.

On Microsoft's call, CFO Amy Hood noted efforts to grow Microsoft Azure's geographic footprint are contributing to its capex growth, as is general demand growth for Microsoft's cloud services.

4. Alibaba and Tencent Are Growing Capex Strongly Off of Smaller Bases

With the qualifier that this figure also covers real estate and content license purchases, Alibaba's (BABA) capital expenditures rose 39% annually to $1.81 billion. Tencent (TCEHY) , meanwhile, saw its capex rise 71% in RMB to RMB5.97 billion ($862 million)

5. Intel, Nvidia and Arista Are Still Seeing Healthy Cloud Spending Trends

Intel's (INTC) Data Center Group (DCG), which handles sales of server CPUs and other data center products, saw its sales to cloud service providers rise 50% annually in Q3. And though it cautioned DCG's cloud sales can't be expected to grow 50% forever, the chip giant suggested cloud demand remains good.

Nvidia's (NVDA) Datacenter segment, which covers sales of server GPUs and hardware to both cloud providers, posted revenue of $792 million. That was a little below analyst expectations, but still good for 58% annual growth. The business continues getting a big lift from the large investments cloud giants are making in GPU-accelerated hardware that's used to train AI/deep learning algorithms, and is also seeing sales of GPUs used to run those trained algorithms against real-world content pick up.

Arista Networks (ANET) , a major provider of data center switches to cloud giants, beat Q3 estimates on the back of 29% revenue growth and issued in-line Q4 sales guidance. On Arista's call, CEO Jayshree Ullal suggested demand from "cloud titans" remains strong, albeit while cautioning Arista's sales to these firms "don't track one-to-one" with their capex.

6. Hard Drive Makers Are Seeing a Slowdown in Cloud Orders

Western Digital (WDC) raised eyebrows in October when it cautioned that it's seeing a "temporary slowdown" in hard drive demand from "large cloud service providers," and would only forecast demand would get better in the second half of 2019. Not long afterwards, archrival Seagate (STX) warned it saw a "digestion cycle" begin for cloud-related hard drive purchases during the September quarter, and said its "best estimate is that [the cycle] may last for up to three quarters."

Though such buying cycles are indeed a fact of life for many cloud suppliers, it's possible that -- as noted by Mizuho analyst Vijay Rakesh while going over Seagate's earnings -- a recent plunge in NAND flash memory prices could also be weighing, by making solid-state drives (SSDs) more price-competitive with hard drives. Research firm DRAMeXchange recently forecast NAND prices will see a fresh double-digit sequential drop in Q4.

The Big Picture

Data center capex is by its nature very lumpy from quarter to quarter for individual companies. Annual growth can swing a lot based on the timing of major hardware orders or construction work, and also based on when a company chooses to pause its purchases to work through its existing assets.

Nonetheless, looking at the group as a whole, cloud capex trends still look fairly healthy. While spending growth could slow a bit in 2019 from 2018's sky-high levels, the demands placed on cloud infrastructures by secular trends such as public cloud service adoption and online video consumption, as well as by the computing demands imposed by the complex algorithms (including AI-powered algorithms) that are powering many consumer services, makes it likely that cloud capex will still rise at a healthy clip over the next few years.

It also doesn't hurt that many of the companies responsible for much of this capex are still growing their Internet and cloud-related revenue streams at 20%-plus clips. Unlike, say, telecom service providers that have been struggling to deliver positive service revenue growth, there's a strong revenue foundation in place among cloud giants for collectively spending a lot more on capex 3-to-5 years from now than they do today.

Alphabet, Facebook, Amazon.com and Microsoft are holdings in Jim Cramer's Action Alerts PLUS member club.

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