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Motherboards With More Slots Sought
cheros writes: "I would be interested if anyone knows of motherboards which have more than the usual 4/5 PCI slots on them (and maybe with one or two ISA slots as well). Extenders would be interesting too, but I can imagine bus timings getting in the way of anything with leads leaving the case. I'm about to build another system (with a 1.3GHz AMD as main processor), and when I start listing the toys I want in it I end up being short of slots. Just add up: sound, SCSI, NIC, TV, FireWire, serial card for extra serial ports (Linux and VT100 - it rocks ;-). And I have this old ISA card I built a while ago with 8 relays - that's no longer usable so I might need another slot for a digital I/O card. Anyone? Pleeze?"
About 6 is the absolute maximum number of slots you can get on a PCI bus segment. There are a limited number of "loads" that a PCI bus can support, usually about 10-12 max. The connector counts as a load and the card itself is a load. To go greater than that, you have to have a PCI-PCI bridge. Unfortunately, when you have to go across a bridge, your performance goes down. Because of the way PCI works, transfers on the bus must be interruptible. If the transfer is going across a bridge, you will gain latency when the bridge has to re-negoitate the transfer.
PCI-X has improved this, but right now, PCI-X devices (and motherboards) are pretty rare. You can't mix PCI and PCI-X on the same bus segment without the bus segment downgrading to PCI functionality.
Also, according to the PCI spec, a card can draw up to 25W, which increases the size of your power supply.
The best bet is to go with a motherboard with some integrated functionality- as others have said, compatability is an issue, but there are motherboard makers out there who use high quality parts (which are well supported in Free-OSes), Adaptec for SCSI, Intel for ethernet, and so forth, but you're going to have to pay more for it.