Cyber-sleuthing can be both fun and profitable.

When Cirrus Logic (Nasdaq: CRUS) announced weak preliminary earnings last month, the culprit was production issues with a new audio chip. At the time, I figured that Apple (Nasdaq: AAPL) probably wasn't the customer for that chip because of timing issues between launches of its popular iPad and iPhone products.

Production problems for a new chip design in March didn't make sense if the target device were an iPad 2 already on its way to your neighborhood Apple store. And it was a bit early to produce audio chips for an iPhone 5 not slated for release until mid to late summer.

But I forgot about another major Apple product line with a regular update schedule: the iMac.

When iFixit ripped a new iMac apart last Wednesday, it found a powerful quad-core Intel (Nasdaq: INTC) processor and a gaggle of chips from Broadcom (Nasdaq: BRCM). Advanced Micro Devices (NYSE: AMD) maintains its stranglehold on Mac graphics, as you can't even select NVIDIA (Nasdaq: NVDA) graphics as an upgrade. The quad-core Intel chip is a Sandy Bridge model, which stumbled on faulty support chips much to Intel's embarrassment. Apple appears to have worked around that design flaw in the iMac.

That's all very good, investable information given that Apple still ships about 1.2 million desktops, including the iMac line, per quarter. But that's not what I came to iFixit for this time.

Then there was the audio chip -- a Cirrus Logic 4206BCNZ. Stop the presses! This is very likely to be the chip that caused Cirrus to stumble.

The 4206 line of audio chips is an Apple-specific version of the 4207 chip that Cirrus sells to anybody. Cirrus doesn't generally promote or sell the 4206, but an earlier version showed up in the recently refreshed line of Apple MacBooks and the Mac mini from the summer of 2010. That one was called 4206ACNZ. The lineage is clear, and about eight weeks of lead time from March matches up nicely with the iMac.

If nothing else, this episode highlights just how tightly Cirrus Logic has tied its fortunes to Apple -- and how far backward it will bend over to keep Cupertino happy.

So there you have it: Don't hold your breath waiting for an amazingly high-volume gadget from Motorola Mobility (NYSE: MMI) or Samsung featuring a brand-new Cirrus audio chip. It appears to be Apple after all.

Learn more about Apple's parts suppliers:

Fool contributor Anders Bylund owns shares of AMD but holds no other position in any of the companies discussed here. Intel is a Motley Fool Inside Value pick. Apple and NVIDIA are Motley Fool Stock Advisor recommendations. Intel is a Motley Fool Income Investor choice. The Fool owns shares of and has bought calls on Intel. Motley Fool Options has recommended a bull call spread position on Apple. Motley Fool Options has recommended a diagonal call position on Intel. Motley Fool Options has recommended writing puts on NVIDIA. The Fool owns shares of Apple and Cirrus Logic. 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. You can check out Anders' holdings and a concise bio if you like, and The Motley Fool is investors writing for investors.