Hardware Considerations

Some hardware considerations are dealt with in this section, namely choice of motherboard, vga cards, audio cards.

The following issues are worth considering when purchasing equipment.

1. MOTHERBOARDS:

   The more available PCI slots the better, especially for single machine nodes. If using a newer high performance VGA card, the motherboard should have appropriate AGP performance to make use of it.

   Dual processor motherboards are preferred but not essential. P4 processors are only available for dual operation in the Xeon configuration. Newer dual Xeon motherboards often have a mixture of 32bit and 64bit PCI slots. While some 64bit slots can accomodate 32 bit cards, the results may not be predictable and a motherboard with all 32bit PCI slots is recommended. The only dual Xeon motherboard with a reasonable number of 32bit PCI slots (five) currently known to be available is the Tyan Tiger i7505 (S2668).

   A number of single P4 processor motherboards exist with six available 32bit PCI slots.

2. VGA CARDS:

   Four VGA outputs are required to achieve the single control monitor and three projected outputs of a standard Access Grid node. While this can be achieved with a single Matrox G200 PCI card, its performance is limited by the bandwidth of the PCI bus itself. The table below gives the bandwidth of various bus types showing why it is preferable to use the AGP slot as much as possible. A dual output Matrox G450 or G550 AGP card combined with a dual output G400 PCI card is a common configuration.

   Our interest in running hardware accelerated visualisation and graphics applications in an Access Grid context has led us to use nVidia based cards. Any of the Quadro4 series give excellent accelerated performance. The newest of these cards require an 8x AGP slot. They are generally dual output and are used together with two additional single output PCI cards. When using AGP and PCI cards together like this, it is preferable to use cards based on chips from the same manufacturer. This simplifies installation of drivers for the cards.

   Table 1. Bandwidth of various bus types

   BUS type	Bandwidth
   PCI	133MB/s
   AGP 1x	266MB/s
   AGP 2x	532MB/s
   AGP 4x	1.05GB/s
   AGP 8x	2.1GB/s

   A new, yet to be released, bus standard "PCI Express" will have a bandwidth of 8GB/s.

3. AUDIO CARDS:

   An audio chip capable of full-duplex operation is required. Many motherboards already have audio chips available on board. If a suitable driver is available for an on board chip then no additional sound card is required, making an extra PCI slot available for other purposes. If an on board chip is not supported and an additional card is required, ensure that the motherboard BIOS is capable of disabling the on board chip.

   The Soundblaster PCI-128 is a cheap but adequate audio card commonly used in Access Grid installations. Both ALSA and commercial OSS drivers are available for this card.