PCI or PCI-X - How do i tell?

Hi benjamingordon-

You have PCI slots.

See for yourself here: Power Mac G5 (Late 2004) - Technical Specifications

Luck-

-DaddyPaycheck

Hi-

If you buy a new tower now, or in the near future, it will have PCIe (express) expansion. This is yet faster than the PCI or PCI-X, but not compatible with PCI or PCI-X.
In the PCI-X G5, you have one 133mhz slot, and two 100mhz slots. Regular PCI is only 33mhz. The benefits of the PCI-X slots are that you can use faster expansion cards to take advantage of the higher bandwidth. PCI-X is also backward compatible to PCI, giving you a wide variety of available expansion choices.

Thats great, but i would like to be able to work out for myself which machines have which PCI cards?

I like either Apple Support Specifications or Everymac.com. Note that Apple's specs list all slots as PCI even when they're PCI-X. You have to look at the bus frequency and bus width to really determine the PCI-X slots.

Is PCIe also back compatible to the PCI-X and PCI cards?

No, they are physically incompatible with each other.

How fast is PCIe by the way? Also, on the PCIX machines, there is only 1x 133MHz and 2x 100MHz. On the PCIe does it have 1x fast and 2x slower PCIe expansion slots? Also, how do you tell which one is faster?

PCIe slots have a certain number of "lanes" that they use. Each lane is capable of transmitting approximately 250MB/sec. So, a 4X PCIe slot is about the same speed as a 64-bit PCI-X slot that's running at 133 MHz. A 1X slot is about double the bandwidth of a standard 33 MHz, 32-bit PCI card. 8X PCIe is about the same speed as 8X AGP.

On my G5 with PCIe slots, it has one 16X slot (for the graphics card), one 8X slot, and two 4X slots. The 1st generation Mac Pros have variable speed slots and the current Mac Pros have two 16X slots (PCIe 2.0 spec) and two 4X slots.

Also, is there any option to install more than 3 extra PCI cards?

With the use of an expansion chassis, yes. Magma has quite a few to choose from. They're not cheap, so keep that in mind. Are you in danger of running out of slots to use? If so, what do you already have installed?

I thought that there was some way to open up the machine and see an ID label which would indicate whether it was PCI or PCI-X and now PCIe?

There's a label on the chassis just below the clear plastic air deflector. I believe that will show whether or not you have PCI or PCI-X slots. However, on my G5 with PCIe slots, it does not mention this anywhere.

There were only two models of G5 that had dual 1.8 GHz CPUs. The ones released in November 2003 (and discontinued in June 2004) have PCI-X slots, but the dual 1.8 GHz machine that replaced it (the "June 2004" model) has regular PCI slots.

I have just ordered 2 USB expansion PCI cards as i seem to have millions of USB devices.
I also want to install a firewire one as i have lots of firewire devices daisychained.
Im going to install a PCI card for my MOTU interface when i buy it and i also want to buy a UAD plugin card.

With all those cards that you want to buy, you'd need two extra slots that you don't have. If you install the MOTU and UAD cards, you've only got one slot left. I wonder if you'd be better off filling that last slot with a USB/FireWire combo card and using USB and FireWire hubs to connect all your devices. With the built-in USB and FireWire busses in addition to those added by the cards, you'd have quite a bit of bandwidth for all your devices.

Im also planning to buy one of the latest G5s when i come into some money. Does this mean i will have to re-buy my USB/firewire and UAD plugins PCI cards as PCIe cards?

Just as an FYI, the new Mac towers are called the Mac Pro and are quite different from the G5 although they look very similar from the outside. All cards that are inside your current G5 will not work in a new Mac Pro, as they all use PCIe slots which are physically incompatible with the older PCI/PCI-X slots.

In that case i cant remember exactly when i bought mine and i didntbuy it direct from apple. I bought it from an apple dealer. In this case i dont know how to tell whether mine in the PCI or PCI X. Its very confusing. . .

Do you still have your invoice? Presumably is has the Apple SKU on it somewhere. M9393LL/A is the PCI-X model, and M9454LL/A is the PCI model. It's possible the SKU is also on that label I mentioned in a previous post.

So if i bought a new computer id have to buy all new PCIe cards. . . Simple as that? No option. . .

Well, you could purchase one of those expansion chassis. Magma makes some for PCI/PCI-X cards that hook up to a PCIe card in the host computer. So, that would theoretically allow you to continue using your existing cards in a new PCIe machine. However, most of those chassis cost between $1,400 and $2,200, so it'd probably be a lot less expensive to repurchase the cards. Do any of the manufacturers such as MOTU offer trade-in programs?

If i used a PCIe firewire/USB combo then used hubs would the connections be faster than if i just connected firewire and USB hubs to the computers built in USB and firewire ports?

There would be no speed differential. However, adding a FireWire/USB combo card adds a second FireWire bus and a second USB bus to the computer. When you plug in a hub to the built-in ports on the computer, each device plugged into the hub has to share the total bandwidth of that connection with every other device plugged into the hub or the other built-in connections. Although your computer has three total built-in USB ports, those three ports are on the same bus and can only provide a total of 480 Mbps of bandwidth. With a card installed, now you have two USB busses that can each provide 480 Mbps of bandwidth to the connected devices. So, fewer devices on each bus fighting over the bandwidth. Of course, you could always just leave most of the devices unplugged and only plug them in when needed. Then you probably wouldn't need all the hubs in the first place.