Speed of PCI 32bit

[boles]

What is the max speed of the PCI bus?

Reason I ask is that I have a SCSI (U320) card and drive (15K) that is sitting around. I thought about putting it in my box to increase overall performance but then I started to think that the PCI bus is only good for 100 mb/sec (I think) which would in fact be slower than SATA transfer.

Will I get any really good results from doing this?

 

[Vegito]

At 32-bits and 33 MHz, the throughput rate of 133 MBps (at 66 MHz 266 MBps).

PCI 33 MHz
PCI-X 66 MHz - 64 Bit @ 532 MBps

 

[BTRY B 529th FA BN]

ive only seen a few MB's with the PCI-X slot and they are not performer boards. Usually server boards. I will increase performance if the drive is good for single user performance but if you want to run a data server off it, well then i don't know...

Good luck

 

[Cerb]

You'll be fine. Even nice new SCSI drives have trouble going over 70MB/s sustained. You'll be waiting on PCI when doing bursts, but not enough to converned over--it will still be faster than a typical ATA drive, and feel even faster than benches will show.

One thing: IIRC, some VIA chipsets couldn't handle much PCI traffic. I think MechBgon did some tests on this (I'm thinking ~55MB/s vs. 120+MB/s for NF2).

 

[dwcal]

Originally posted by: Cerb
You'll be fine. Even nice new SCSI drives have trouble going over 70MB/s sustained.

Yeah, a single drive won't max out the PCI bus unless the MB chipset has serious performance problems. 133MB/s is the theoretical max, but it's shared with all the other PCI devices. Still, it should easily handle 70MB/s.

 

[mechBgon]

My peak real-world PCI throughput on nForce-family boards has typically been ~120MB/sec. SCSI's real advantage isn't simply high sustained-transfer rates, but "cornering capability." 0.2ms track-to-track, sub-4ms average seeks, working command queueing, that's where it will put the hurts on ATA

For perspective, I did a real-world task with my ancient Quantum Atlas 10k (first-gen 10000rpm SCSI). Its peak sustained throughput is only 24MB/sec. Nevertheless, it beat an 8MB-cache ATA drive (with about twice the sustained transfer rate) by about 10% in my timed test. Ouch! :evil: Granted, the ol' Atlas 10k does sound like the hybrid offspring of a jet engine and a can of BB's being shaken... but they've come a long way since then

 

[boles]

I currently have sata 7200rpm raid 0 right now but was thinking that setting up this scsi drive would give me better overall performance loading games and overall use.