MoboSpec Meaning

L

Luckyme

Geek Trainee
What does PCI Express x 16 x 2 PCI x 3 PCI Express x1 x2 mean. and PCI-X i saw somewhere else mean?
PCI Express (16 and 1) have Mbs transfer rates of 100Mbs -- is that right? The 16 is where the two graphics card would go -- is that right? what goes in the x1? In a 64 bit Mobo (e.g., P5ND2-Sli) the 3 plain old PCI slots are 32 bit -- is that right? looking at some SCSI cards, they appear to either go in a PCI-X slot (what/wherever that is), or, if connected directly to the mobo to the PCI slot -- is that right? If a dual channel Ultra 39360 SCSI can burst at 1G per second and sustain at 89 Mbs won't the PCI blow up?
 
Okay basically PCIe aka PCI-Express 16x is the current standard for graphics cards. When you see PCIe x16 x2 it's saying that there're 2 separate 16x slots. PCIe 1x is a much smaller slot that is currently pretty much useless, in the future it will replace standard 32-bit PCI slots. There's also PCI 4x which is basially a beefed up 1x slot that, again will offer expandibility for sound cards and the like.
You will also see the term SLI which refers to motherboards that have two PCIe slots. The idea is you insert two cards and can run them in tandum with a special bridging card for a great increase in performance. However, up untill recently when running two cards at once the PCIe 16x slots became PCIe 8x slots, reverting to a slower speed. But now on very new motherboards you may see that SLI mode will give you two lanes, both running at 16x when two cards are used (when one card is used it will always run at 16x speeds regardless of make of model of the motherboard, so long as it has the PCIe slot).
Hopefully that made sense, I know it is very confusing:)
 
The PCI-X (PCI eXtended) has been around for quite awhile and is found on workstation and server motherboards. Not to be confused with the more recent PCI Express (PCIe/PCI-E). PCI-X slots are 64-bit 66-,100-,133-,266-, or 533MHz slots, and it's not uncommon to see motherboards with different speed PCI-X slots and busses on one board. A 66MHz card can be put into a 133MHz slot, but the bus would only function at 66MHz. Any other devices on that bus would run at 66MHz.

PCI-X devices commonly are able to run at slower speeds than what they are rated for.

The PCI bus is a 32-bit bus that runs at 32MHz, resulting in a whopping 133MB/s. (bit x MHz/8=MB/s). Plug in other numbers and have fun.

As you mentioned a burst of 1GB/s...that's the burst rate, which is much slower than the sustained transfer speed. Actually disk drives (SCSI or otherwise) tend to run more between 40-80MB/s. If you put a lot of SCSI drives on one chain (say 8 Seagate Cheetah 15k RPM ones), then you'd start to get up there, but you might only hit those high speeds by running a RAID 0 or 5 array.

Even then, the card wouldn't blow up. The limitations of the bus would kick in first. As long as the buffer was there to keep the unprocessed/sent data there, you wouldn't have a problem. High-end cards tend to feature an RAM slot to drop in some RAM for caching purposes. Now, if you had some electrical malfunction (like putting a 3.3V card into a 5V slot that could only run at 3.3V), then, yes, you'd be asking for problems. However, most PCI-X slots are 3.3V now anyway.
 
Good work B, I forgot to explain what PCI-X was used for but you did a much better job than I ever could have :good:
 
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