All RAM radiates heat, and the more bits, the more transistors are busy turning electrical energy to thermal energy.
Did you 1 Gb module have on it rectangular chips with pins running up either long edge? Or square small chips with no visible pins (sometimes the small chips are coated with a black coating that liiks as if it was poured on)?
The larger, rectangular chips are the old-style TSOP construction, these throw more heat than the new MBGA (Micro Ball Grid Array) construction with the small thin square chips. (and because more heat is wasted, more battery power is used up)
The MBGA design doesn't have pins, because the connections are made with a grid of solder "balls" on the underside of the chip, that mate with a grid of depressions on the circuit board. Think of two ice cube trays, one inverted on the other, with a golf ball in each cavity. The golf ball is the solder that aligns and connects the chip's contact to the corresponding board contact. Because the chip is smaller and more efficient, it runs at a lower temp.
(Sorry, I just happen to think stuff like this is cool...)
If you are being offered 1 Gb modules in the TSOP format, you know these are older, obsolete modules. TSOP is still used in smaller capacities of SODIMMs and in DIMMs, although we are starting to see MBGA DIMMs coming on the market.
Thanks,
Trevor
CanadaRAM.com