Grain Of Salt

[DCB_AU]

Most solution replies to PC problems at these forums are correct and very helpfull, however some should be taken with a "GRAIN OF SALT"- INCORRECT!

I recently asked a question if you could obtain PCI to SATA Adapter Cards and was told- implied that you can't get them and it was a silly question as SATA runs at a higher speed- 150 and PCI Bus is a lot slower.
We all no that the PCI bus is slower than SATA and if you could get a adapter card there would be no if any performance improvement.
The improvement I was looking for was cable and air movement.
Anyway, you can get these adapter cards and they do what I wanted. There called HighPoint Duel-Channel PCI to SATA Host Adapter Cards, eg. (RocketRaid 1520).

<font color=red>DCB</font color=red><font color=white>_</font color=white><font color=blue>AU</font color=blue>

 

[Javic]

There are actually many brands of SATA PCI Adapter cards. All you need to do is look around.

 

[Crashman]

Who said that? All I've ever said is that it isn't worth it, because ALL PCI devices are limitted to 133MB/s max (even onboard PCI devices), the drives aren't fast enough to take advantage of the added speed if it did exist, and all the associated parts are expensive.

In fact Tom's even did a review on PCI SATA cards. And several of his reviews have included SATA to ATA adapter cards. All this stuff is now months old.

<font color=blue>Watts mean squat if you don't have quality!</font color=blue>

 

[aliu42]

How can a PCI device be limited to 133MB/s? How do you explain RAID then?



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[Hoolio]

Hmm I thought the throughput was 2100MB/s (doh! must have been thinking of DDR ram!)

So may I as what the point of Ultra Wide SCSI card with a throughput of 320Mb/s is? (Except the fact devices to talk to each other very fast) I know they are available as 64bit PCI too!
<P ID="edit"><FONT SIZE=-1><EM>Edited by Hoolio on 04/13/03 08:59 AM.</EM></FONT></P>

 

[Hoolio]

I am surprised then there are not more firewire devices out there......you could run a Graphics card over firewire in theory!

 

[Crashman]

Do the math. A PCI slot runs at 33MHz and the slot is 32-bits. Now 32 bits is 4 bytes. 4 bytes * 33MHz = 133MB/s.

You obviously don't understand the fact that UDMA 133 drives, as well as SATA150 drives, actually only transfer at around 50MB/s MAX continuous rate. RAID level 0 on 2 drives can give you twice the rate in theory, but 100MB/s continuous transfer is still less than 133MB/s.

I know you're going to try to prove me wrong, so do the math first.

Now here's a little more to rattle your cage: A lot of guys are counting on onboard SATA150 controllers to exceed the limits of a PCI slot: that won't work because the controller is still connected as a PCI device! They simply omit the extra slot and run the 32-bit 33MHz connection directly from the southbridge to the SATA controller for onboard controllers, the math still works the same.

<font color=blue>Watts mean squat if you don't have quality!</font color=blue>

 

[Crashman]

64-bit PCI is 266MB/s. 66MHz 64-bit PCI is 533MB/s. Many of these SCSI controllers are being used on the 266MB/s slot, but that's still faster than Ultra 160.

Firewire transfer is measured in megabits, not megabytes. A 400Mb firewire connection is only 50MB/s! That's certainly fast enough for most drives, but not half as fast as a PCI card. And don't forget that AGP4x has 8x the bandwidth of PCI, more like 20x the bandwidth of Firewire!

<font color=blue>Watts mean squat if you don't have quality!</font color=blue>

 

[Hoolio]

Damn forgot that, something I should have noticed really as I do electronics!

I feel really stupid now......(doh!)

That is why I meantioned 64bit PCI, but 266MB/s is still slower than SCSI 320MB/s

 

[lhgpoobaa]

And thats why we really need something like PCI-X or the next super standard to escape from the puny 133mb/sec limitations!

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