PCI 32-bit lateny issues in AMD dual boards...

[MameXP]

Ok i know this has been asked b4 and i DID actually read about it b4. However i didnt pay much attention so now i forgot (well ye i havent played much with my dualie)

Can someone tell me ALL info about this issue ?(links are good)

And How/what should i do to avoid it?

I'm currently use all PCI-32bit slots on my board (Asus):

2 x NIC cards
1 x Sound card

Would my current setup be affected by the issue?

Thank in advance
MameXP

[Supertrucker]

from what i gather, you never want to use a pci ide controller card in one of the 33mhz 32bit slots, avoid this at all costs, other than that its ok to use the slots with things that dont require the throughput of a pair of hdd's. you should be fine

[MameXP]

Ye i remember something like that but does it affect NICs tho?
Also i need more details info on this, come on help me out...:(

[cmcquistion]

There is a little documentation in this review (http://www.burningissues.net/hard/iwill/MPX2p4.htm) of the MPX2 motherboard. I don't think the review is very good, but they do have some good documentation of the effect of the issue. (Incidentally, this is the latest (and only, I think) review done by this site and it is over a year old, on a revision of the MPX2 that has never seen mass distribution.)

Basically, it comes down to this: there is a latency issue with the 33 MHz/32 bit PCI bus, which messes up its maximum bandwidth. Those slots SHOULD have a maximum bandwidth of 133 MB/s. The latency issue strangles the maximum bandwidth down to about 40-60 MB/s. For MOST peripherals, like NICs, soundcards, etc, this is a non-issue. Those peripherals never come close to using that much bandwidth, anyway, so the latency issue doesn't affect them. The only cards that this REALLY effects are disk/RAID/SCSI cards. Those cards need to ALWAYS be used in one of the 66 MHz/64 bit slots. It doesn't matter if your disk controller is only 32 bit. Use it in one of the 66 MH/64 bit slots. It will need to be 66 MHz, or 66 MHz PCI slot compatible, though.

I know I've read more information about this issue somewhere else, but I can't remember now, where it was. The only one I could remember was that burningissues review

[Audioaficionado]

I've seen some discussion over at 2CPU.com forums on this known issue. The main thing to avoid like cmcquistion says is anything that needs more bandwidth than the crippled 32/33 PCI slots can deliver.

You can try google and do searches on various related terms. You should be able to find out more that way.

[MameXP]

Thanks all for the inputs.
THis really does remind me lots about the issues now. Hmm so one last concern is it doesnt affect the IDE controller at all right? I' pretty sure it does not but i will check on the anual/whitepaper on AMD site.
Gee school takes all my time now

MameXP

[Rav]

The 66Mhz slot is great. I got a 160GB WD SE drive and used the Promise card that comes in the box. Popped that in the 66/64 slot and it is very fast, faster than any of my other WD SE drivers on standard IDE controllers. At least in my objective use. I work with multiple, multi-gigabyte files off that drive and it doesn't flintch. I can't wait to set up my server with RAID5 SATA which will of course love 66Mhz. So, if there are issues though I'd like to know.

-Rav

[cmcquistion]

No, the issue does not affect the onboard IDE.

[MameXP]

OMG Rav, you are my man! :D Looks all your systems in you sig. They're all AMDs. You are truly an AMDroid. I'm so proud of you

To others: hmm ye i got stuck in my CS assignment so i just saying non-sense stuff blah..
sorry bothering you guys
;) time to go back to MIPS :p