64bit PCI - What's the deal?

[Jules48]

I'm about to build a PIII system based around a Serverworks chipset on either a Supermicro or Tyan Thunder server mobo. I just had a couple of dumb questions which somebody may be able to help me with:

1. Some of the main boards under consideration don't have any 32bit PCI slots, they have say 2 64bit 66MHz slots and 4 64bit 33MHz slots. I've been told that I can still use 32bit PCI cards in the 64bit 33MHz slots. Is this bullshit, i.e. do I actually need a board that has 32bit slots?

2. Some of these boards claim to effectively run two independent PCI buses to avoid bottle-necks. This is critically important to me. What I'm hoping to do is run my disks (via SCSI or Raid) on one bus - I guess the 66MHz bus, and my pro-audio hardware on the 33MHz bus. Is this feasible in reality? Does this mean I need a special 64bit 66MHz Raid or SCSI controller (if they exist) or will the on-board controllers typically be using the 66MHz bus anyway? If not, what's the 66MHz bus there for?

Many thanks in advance for any pointers here. This is the end of a long search for a PC spec'that would give me maximum PCI bus performance for use with Creamware's range of audio hardware (notably PCI bus demanding), so I'll spare the other details.

Jules

 

[Argo]

I didn't know they had 64bit 66MHz PCI slots...

 

[Sunner]

Yep there are 64/66 PCI slots.
There's no problem with using 32 bit PCI cards in 64 bit slots.

As for the second question, some mobo's do indeed use several controllers to avoid having too many cards share the same bandwidth.
And if you wanna take advantage of the 66/64 PCI ubs, you will ned a card that can handle both 64 bit, and 66 MHz PCI, most high end server controllers do this, I dont know any high end consumer ones that do though, but that isnt exactly my area of expertise, there might be some out there.

 

[VladTrishkin]

64/66 PCI's are rare now-a-days, but i saw some DSL modems that use them.

 

[thorin]

It's just like using a 8bit ISA card in a 16bit EISA slot.

Thorin

 

[PCResources]

<< 64/66 PCI's are rare now-a-days, but i saw some DSL modems that use them. >>



There are many more cards than DSL cards using the 64/66, some gigabit ethernet controllers, some RAID controllers and then there is a whole lot of audio/video cards using 64/66.

There will be more because the demand for bandwidth over the PCI bus is getting bigger and bigger.




<< Some of these boards claim to effectively run two independent PCI buses to avoid bottle-necks. This is critically important to me. What I'm hoping to do is run my disks (via SCSI or Raid) on one bus - I guess the 66MHz bus, and my pro-audio hardware on the 33MHz bus. Is this feasible in reality? Does this mean I need a special 64bit 66MHz Raid or SCSI controller (if they exist) or will the on-board controllers typically be using the 66MHz bus anyway? If not, what's the 66MHz bus there for? >>



Using more than one PCI bus is a great idea, so this would fit your needs perfectly.
I would suggest you look at the server RAID controllers instead of using the built-in ones, because very few of them are using the 64/66 bus interface. I believe that your thoughts about using the 33Mhz bus for your audio and the 66Mhz bus for your RAID are correct, you will get maximum performance out of such a design.

Patrick Palm

Am speaking for PC Resources

 

[Windogg]

As a side note, some Serverworks cannot take unbuffered SDRAM and required registered DIMMs to work.

Windogg

 

[Jules48]

Patrick - thanks alot for your input here. It sounds like I may finally be on the right track with a dual bus setup. I'll look into 66MHz/64bit controllers and start getting a spec' together.

Windogg/Patrick - spot on about unbufferd/registered DIMMS, I noticed that too. What impact does this have specifically? Is this a big price issue, will it affect performance, or did you mention it just to make sure I get the right sticks of RAM?!

Thanks again.

Jules

 

[samgau]

I ran into the ram issue recently, I have a compaq proliant server that will take only registered dimms...anything else and it would just stop on boot complaining about the presence of unregistered dimms populating (polluting more like it) its dimm slots.... now get this, 512 Mb of PC100 registered dimms at compaq runs about $1600 last time i checked...i got em for about $800 at micro x press.
You will have to find 66mhz/64bit cards to run in the 66mhz pci slots..they are normally pretty expensive...we are talking here high end RAID array controllers, and as mentioned before gigabit ethernet controllers...( 66mhz/64bit = pretty close to AGP port specs no.. and on a seperate bus too, pci 2 compared to AGP bus )

 

[Jules48]

I see the problem. We're talking RAMBUS prices, which wasn't quite what I had in mind. IF that's the case I guess I may as well hang out for a P4 and go the RAMBastard/I850 route.

Oh well. Back to the drawing board. MAybe there's a server board which doesn't need registered DIMMS?

 

[samgau]

I guess you have to find out which of the boards can accept unregistered dimms... im pretty sure not all of them require only reg dimms.

 

[Windogg]

SAY NO TO RAMBUST!!!

Compaq has traditionally charged for fore their server supplier because of the the pre-fail warranty.

MWave has 128MB Corsair PC133 Registered CAS3 DIMMs for $183.

Windogg

 

[Jules48]

You lost me on the Compaq bit there but the Mwave price looks good. All I've got so far is $1200+ for a 512MB PC133 Reg DIMM from Crucial. I need two of the damn things! From what I can make out all the Serverworks based boards specify ECC registered DIMMS only.

Doesn anyone know of any that will use unregistered?

Thanks

Jules

 

[Windogg]

Sorry Jules.... long day here at the office and my mind (and ability to type) went out the window hours ago. What I meant to say is that the reason Compaq server component prices are so high is because they will exchange a part before it fails. All you need is some suspicion that it might go bad and they send you a replacement part via overnight mail. All that comes at a caost which means way inflated prices.

I have always known Serverworks boards to only take Registered DIMMs. Your already spending a lot for a server and it needs to be stable. The extra few buck (OK its not a few) is well worth it. Imagine the cost if the server needed to be rebooted every few days.

BTW: Dig that 2MB onboard video.

Windogg

 

[Jules48]

I think you mean 4Mb - just imagine the framerates!!

By the way, $680 for 512Mb registered at Crucial. Not cheap, but a little less scarey then I feared for a while. Maybe I can make this system work after all.

PS. Can I get a 64bit/66MHz PCi graphics card in this baby as well?

 

[samgau]

Just a little clarification, what i bought was 2 sticks of 256 MB ECC REG each for a total of $840... the 512 sticks were more expensive..

 

[PCResources]

<< By the way, $680 for 512Mb registered at Crucial. Not cheap, but a little less scarey then I feared for a while. Maybe I can make this system work after all. >>



And Crucial is probably the best memory you can get, good quality and high performance. This is the memory that i use and recommend.





<< Can I get a 64bit/66MHz PCi graphics card in this baby as well? >>



There are some 64/66Mhz PCI graphics cards out there, but they are all extremely expensive professional cards, i would suggest you go with an AGP card as the AGP bus is a seperate bus so it will not use the bandwidth of your PCI bus, and it has about the same specs.


Patrick Palm

Am speaking for PC Resources