View Full Version : PCI Express Cards - Newbie is confused.

08-12-2005, 10:24 PM
Hi All,

I have acquired a dual EM64T Xeon system (Intel E7520 chipset) which I figure will be a good LW rendering workhorse.

Now I would like to put a half-decent video card so it can also be used for gaming but I am confused by the range of cards out there. :o

The mobo has one 8x PCI Express slot, and one 4x PCI Express slot.

The main question I have is "What are my options for getting good video performance on this machine?"

Here are some specific questions which serve to highlight exactly how confused I am. :) ......

1. How do I tell which cards are suited to the 8x slot? (Has the number of nVidias "Pixels per Clock" or ATI's "pixel pipelines" got anything to do with it?).

2. With SLI, can I run two PCIe cards on this machine?

3. If so, should the cards be identical or is it best to match each card to the speed of the slot.

Any comments would be welcome.

08-13-2005, 02:12 AM
Ohhh... I really really hope that I'm wrong about this, but I think video cards will only fit in PCIe x16 slots. That doesn't mean that a PCIe x8 lane can't handle a video card, but it would need a x16 slot. If your 8x lane has the big x16 slot (as they sometimes do) you should have no problems at all. As a last resort, you could buy adapters to convert your slots to x16 size (but not x16 bandwidth) at: http://www.getcatalyst.com/adapters.jsp

Anyway, I don't think there's much chance that, without an adapter, the 4x will fit a card for SLI to work, but if they both have the appropriate slot and the mobo comes with the little bridge thing for SLI'ing the cards (not al mobos are SLI compliant), then you'd need identical cards and I think they'd both work at 4x (they synch at the lowest speed). You can have two video cards installed without SLI, using ATI's sli-like technology that doesn't need the cards to be identical to synch, but most LW users strongly recommend NOT using ATI cards for LW. You can also use two Nvidias working separately, without SLI, to power 2 (or 4) monitors and they'd each work at their full bandwidth.

08-13-2005, 03:18 AM
Thanks JCG!

From what I can tell, the 8x lane does have the 16x size slot. It has what looks like 4 sections and is about 3.5 inches (9 cms) long. That would mean I can take a PCIe video card?

Sounds like I will suffer some performance loss as a result of having a lower speed lane though (I read that an 8x lane is about equivalent to 8x AGP). Obviously no point in going out and buying the biggest badest video card.

Any card recommendations?

(By the way, I got this thing for less than the price of the CPU's so if this does not work out, I'll get another motherboard with a proper 16x lane (e.g. http://www.tyan.com/products/html/thunderi7525.html) and still be smiling).

Thanks again!

08-13-2005, 05:31 AM
Here's a pic of the four sizes
Yes! If ir's 16x size, it will take a PCIe card!

No performance loss from 8x bandwidth (unkess you're using a 7800gtx at maximum load). Even a 6800 ultra can't fill that up.

Recommendations?... any nvidia card that starts with a 6 is good for LW, but if games are also important to you, I love my 6800gt with great passion.

08-13-2005, 11:27 PM
Great stuff JCG.

Turns out, the dividers that create the "sections" I was refering to can be carefully cut out and then, I will be able to plug in a decent card.

I got a clue from this thread where the guy has the same server:


I'm on my way. thanks for the pointing me in the right direction. :D