What happened

Federal Reserve Chairman Jerome Powell warned today that he plans to keep monetary policy tight "for some time," even if it inflicts "some pain" on American businesses and consumers -- and it seems that was enough to spook growth stock investors on Friday.

As of 1 p.m. ET, shares of computer memory maker Micron (MU 1.00%) are down 4.4% and PC manufacturer HP (HPQ -1.36%) has dropped 7.8%. Meanwhile, HP rival Dell Technologies (DELL 1.51%) is really taking it on the chin, with an 11% loss.  

So what

If the Fed chair's comments were the only thing driving the stock market today, though, these tech stocks might not be suffering so much. With the Fed's targeted interest rate already up more than 2 percentage points so far this year, policy is pretty tight already, and Powell's statement doesn't necessarily mean he plans to keep hiking rates by 75 basis points per raise. There's even some talk that the next rate increase might only be a half a percentage point.

Problem is, there's an even more specific factor dragging down shares of Micron, HP, and Dell today -- and Dell's to blame for it.

Last night, Dell reported its Q2 sales and earnings numbers, and while earnings looked good enough ($1.68 per share, pro forma, where Wall Street had predicted $1.64), sales came in a bit short of expectations at $26.4 billion.  

Now, even though this number missed sales estimates, it still showed 9% year-over-year growth at Dell, and operating profits increased 25%. The bad news is that earnings when calculated according to generally accepted accounting principles (GAAP) fell 15% year over year, and at just $0.68 per share, were way below the headline pro forma figure of $1.68 per share.  

Now what

The other bad news is that Dell's two co-chief operating officers, Jeff Clarke and Chuck Whitten, tag-teamed to comment that Q2 was "increasingly challenging" for Dell, and characterized by "more cautious customer behavior as the quarter progressed." Consequently, while management still thinks it can hit Wall Street's earnings target for next quarter ($1.65 per share), Dell warned that its revenue is going to miss expectations by a large margin, coming in nearly $2 billion short of analysts' hoped-for $26.3 billion.  

And this, in a nutshell, is why all three stocks are down today. While business spending seems to be holding up quite well for Dell, the individual consumer is a problem, and that portends sales weakness not just for Dell, but for HP, too. And as a supplier of memory for PCs regardless of brand name, for Micron could also take a hit.

But let's end on a positive note: Even if investors are interpreting these developments as deeply negative today, the bad news has arguably been baked into the stock prices of Dell, HP, and Micron already. Each of these stocks trades for less than seven times earnings currently -- 6.1 times earnings for HP, 6.6 for Micron, and 6.9 for Dell. Granted, those valuations will go up as earnings go down, but still, there seems a fairly sizable margin of safety in each of these stocks at current prices.

For investors with the patience to wait until the next upswing in PC demand, I see a lot of potential in all three.