Kilobit per second to Gigabyte per second

Audio codecs compress sound into a stream of bits played back in real time, so the natural unit is bits per second. At 128 kbps, an MP3 encoder allocates 128,000 bits to represent each second of audio. Higher kbps means more data per second, better quality, and larger files.

Technically yes — dial-up ISPs like NetZero still exist in the US, and some rural areas with no broadband rely on them. But at 56 kbps, loading a modern webpage (average 2.5 MB) would take over 5 minutes. It is functionally unusable for anything beyond basic email.

At 128 kbps, the encoder discards more audio detail — cymbals sound washy, stereo imaging narrows, and quiet passages lose nuance. At 320 kbps, most listeners cannot distinguish the MP3 from the original CD in blind tests. The file is 2.5× larger but audibly transparent to most ears.

A standard VoIP call uses 8–64 kbps depending on the codec. The widely used Opus codec delivers excellent voice quality at 16–32 kbps. Traditional landline phone calls used 64 kbps (G.711 codec). HD Voice on modern smartphones uses about 32 kbps with the AMR-WB codec.

The screeching was the modem handshake — two modems negotiating their connection speed by exchanging test tones over the phone line. Each phase of the screech tested different frequencies and protocols. The modems were literally talking to each other in audio, finding the fastest kbps rate the line could support.

CPUs constantly shuttle data between RAM and their caches. DDR5-6000 provides about 96 GB/s of bandwidth in dual-channel mode. In games, insufficient RAM bandwidth causes frame drops during complex scenes. In productivity tasks like video encoding, it directly limits how fast the CPU can process data.

Thunderbolt 4 runs at 40 Gbps, which is 5 GB/s. Thunderbolt 5, released in 2024, doubles this to 80 Gbps (10 GB/s) with a burst mode up to 120 Gbps (15 GB/s). This is fast enough to run an external NVMe SSD at near-internal speeds.

Both, depending on generation. A PCIe 3.0 ×4 interface caps at ~3.5 GB/s, bottlenecking modern NAND. PCIe 4.0 ×4 raises this to ~7 GB/s, and PCIe 5.0 ×4 to ~14 GB/s. The drive's NAND flash and controller also have limits — the fastest SSDs and the fastest interfaces are in a constant leapfrog.

GPUs use wide memory buses (256–384 bits) with very fast HBM or GDDR6X memory running at high clock speeds. An RTX 4090 has a 384-bit bus with GDDR6X at 21 Gbps per pin, totalling 1,008 GB/s. HBM3 in data center GPUs achieves 3,000+ GB/s through stacked memory with 4096-bit buses.

At multi-GB/s rates, CPU processing speed, software efficiency, and thermal throttling become bottlenecks. A 14 GB/s PCIe 5.0 SSD can deliver data faster than most applications can consume it. Decompression, parsing, and memory allocation in software often cannot keep up with raw storage bandwidth.