Investors are bargain hunting for beaten-down tech stocks.

$Roku Inc(ROKU.US)$ $NVIDIA(NVDA.US)$ $Advanced Micro Devices(AMD.US)$ $Shopify Inc(SHOP.CA)$ While investors are optimistic this week, the prevailing mood can turn on a dime, so Nvidia, Shopify, and Roku shareholders should buckle in for a bumpy ride, as there's likely more volatility ahead.

Nvidia's livelihood depends on consumers and businesses buying its graphics processing units used in video games, cloud computing, and data center applications. If the downturn persists, demand could soften further. Likewise, Shopify has taken it on the chin as shoppers returned to in-store shopping, resulting in slowing adoption of e-commerce.

These factors and the broader economic upheaval have weighed on Shopify, Nvidia, and Roku's stocks, and expectations of further pain ahead have kept many investors on the sidelines, resulting in some compelling price points. That isn't to say these stocks won't fall further -- they likely will. Yet calling a bottom almost never works and these stocks are currently trading at their cheapest valuations in years, so the time to act is now.

Still, these high-growth stocks aren't for everyone. Nvidia and Shopify still aren't cheap in terms of traditional valuation metrics, currently selling for 10 times and six times next year's sales. Roku has fallen into bargain basement territory, with its price-to-sales ratio hitting 2.