- Introduction
- PCI-Express Versus PCI
- The 'X' Factor: PCI-Express Lanes
- Two Flavors of Desktop PCI-Express: x1 and x16
- What You Need to Join the PCI-Express Revolution
- The First PCI-Express Products
- Conclusion
- For Further Research
Two Flavors of Desktop PCI-Express: x1 and x16
Although PCI-Express is eventually forecast to be available in widths up to 32 lanes wide (PCI-Express x32), the first PCI-Express motherboards are expected to support:
x1 (250MBps)
x4 (1000MBps)
x16 (4000MBps = 250MBps x 16)
As Table 1 suggests, it's obvious that x1 slots will be used to replace PCI slots in desktop PCs and x16 is slated to replace AGP 8x.
Table 1 Comparing PCI, AGP, and PCI-Express Throughput
Bus Type |
Specifications |
Throughput |
PCI |
33MHz, 32-bit |
133MBps |
PCI-Express |
x1 |
250MBps |
AGP |
2x |
533MBps |
PCI-Express |
x4 |
1,000MBps |
AGP |
4x |
1,066MBps |
AGP |
8x |
2,133MBps |
PCI-Express |
x16 |
4,000MBps |
PCI-Express x4, with 1GBps of bandwidth, could be used to host a variety of I/O devices.