To format a computer means that all your data will be lost. Your operating system, programs, emails, drivers, pictures, everything! All of the updates on your programs will be gone, infarct the every entire program will be gone.
This drop in TSH is an attempt to return circulating thyroid hormone levels to normal. So, a test to measure the amount of TSH in your system will usually show lower than normal TSH when the thyroid is overactive. So, in general, LOWER TSH = OVERACTIVE THYROID / HYPERTHYROIDISM.
Such low levels are not always necessary, but decreased T4 and TSH levels are an indication that T4 and RT3 levels are being well depleted (which is often the point of T3 therapy). Hyperthyroidism often causes very low TSH levels and symptoms of hyperthyroidism. Yet proper T3 therapy often causes very low TSH levels without symptoms of hyperthyroidism while providing normal temperatures and a decidedly euthyroid clinical state.