<new answer> The old answer is completely incorrect, it does not tell you about the pins. The 72 indicates that the DIMM is ECC
<old answer>72 pin
Some systems use dual memory channels to access ram, if you dont have a pair of memory sticks, it cant work in dual mode, thus not allowing the system to boot. You can buy special DIMM plugins that fool the computer into thinking there are a pair of DIMMs. The other issue could be if your using registered DIMMs in with unregistered DIMMs
DRAM
DIMMs (Dual In-line Memory Modules) can hold varying amounts of memory, typically ranging from 4 GB to 64 GB per module for consumer-grade RAM. High-performance or server-grade DIMMs can offer even larger capacities, with some modules reaching up to 256 GB or more. The total memory capacity in a system depends on the number of DIMMs installed and the maximum supported by the motherboard.
72-pin SO-DIMMs, 144-pin SO-DIMMs, 160-pin SO-RIMMs and credit card memory
A narrow printed circuit board (PCB) that holds memory chips is typically referred to as a memory module or memory stick. Common examples include DIMMs (Dual In-line Memory Modules) used in computers and SO-DIMMs (Small Outline DIMMs) used in laptops. These modules provide a compact way to integrate multiple memory chips, facilitating efficient data storage and retrieval in electronic devices.
While 184-pin DIMMs and 168-pin DIMMs are approximately the same size, 184-pin DIMMs have only one notch within the row of pins
You can get memory dimms as big as 4 gigabytes and your computer will have three or four slots for a dimm.
dual channels
RIMMs are traditionally faster and more expensive
There are no disadvantages, both are the same. Using one 2gb stick of memory will allow you to add another memory upgrade in the future.
DIMMs (Dual In-line Memory Modules) are generally better than SIMMs (Single In-line Memory Modules) due to their ability to transfer data on both the rising and falling edges of the clock cycle, effectively doubling the data rate. DIMMs also support larger memory capacities and have a wider data bus, allowing for improved performance and efficiency in modern computing systems. Additionally, DIMMs typically have a more advanced design, making them more suitable for contemporary motherboards and applications.
RAM (Random Access Memory), SIMMs (Single Inline Memory Modules), DImms (Dual Inline Memory Modules), RIMMs (Rambus Inline Memory Modules).