In theory any device can store anything, because it is speced to meet an interface, not spec'd for its implementation. Realistically speaking, the answer is more murky. This, by the way, is where SSD's get so interesting because there is no accepted way to tell a SATA SSD to "wipe everything" (edit: no way that is reliably trustworthy, at least)
From what I understand, with any classified hardware, one has "declassification instructions" to declassify the hardware after it is no longer needed. These typically come in the form of a letter from the vendor indicating what operations must be taken before the vendor considers the data irrecoverable. For many devices, this comes in the form of "unplug from power for X seconds," indicating the range of time the government feels memory is volatile enough to warrant special handling. For a long time, the process for harddrives was to run a particular series of wipes, but the process was so brutal few harddrives survived, so they were often just destroyed instead.
One reason one may elect to destroy hardware rather than declassify it is if the cost of acquiring those letters from the vendor is too great compared to the value of the product. If a server farm's worth of RAM is expected to be worth a mere $1000 after depreciation, it might be cheaper to just throw it in the wood chipper when you're done.
Final detail: how valuable is your product? If its worth a mere $10 million dollars, you'll find unplugging the ram at room temperature for a minute or two more than sufficient. If its' worth several hundred billion, you may want to consider the wood chipper. If it's beyond monetary cost, well, its your threat model. Do as you see fit.