The benchmarks shown in previous pages clearly show that the limited bandwidth of the legacy PCI bus forms a real bottleneck for heavy RAID systems. A relatively old Ultra160 SCSI RAID-adapter performed on average 32 percent less when measured in I/O performance under desktop workloads.
Who wants to put more bandwidth-consuming devices on his legacy PCI-bus, like graphics cards, video-editing cards or multi-channel audio cards will lose something in the vicinity of 45 percent of performance. Differences are smaller in the server benchmarks, but this is partly due to the usage of RAID-5 instead of RAID-0.
Tweakers who want a big RAID-array are wise to buy a motherboard that is equipped with a 64-bits PCI-bus. Besides the advantage of more bandwidth the PCI-X mainboards also enable you to use separate PCI-busses thus eliminating conflicts between for instance a sound card and a RAID-adapter. Unfortunately 64-bits PCI-slots are mostly found on expensive workstation mainboards with come with a price tag of about 450 dollars. The cheapest solution for a high-bandwidth system is buying a dual Athlon motherboard based on the AMD 760MPX chipset. These boards can be obtained by forking over about 250 dollars, unless you can get one secondhand. Note that this boards have to do without a lot of features present on modern mainboards, like USB2.0, FireWire and on-board Gigabit Ethernet.
The majority of desktop users will find the prices of workstation class mainboards to be too steep. They will just have to wait for PXI-Express to arrive. This technology promises to be a lot more scalable than the current PCI standard which is still stuck on a maximum bandwidth of 133MB/s. Hopefully the availability of bandwidth will be higher than the demand for it, making bandwidth limitations a thing of the past. Until then manufacturers are trying to bring some relief by connecting (Serial) ATA-RAID and Gigabit Ethernet controllers directly with the Southbridge-interconnect taking away the need to use valuable PCI-bandwidth.
We thank both AMD and MSI for making this review possible by providing us with respectively two Opteron processors and the K8D Master dual Opteron mainboard. Finally we would like to thank original article from dutch to english.