PCI Express riser with high performance graphics card

[yottabit]

Hi everyone,

I'm wondering if anyone has experience running a PCI express riser card such as this one:
http://www.amazon.com/2PORT-PCIE16-L.../dp/B002M1DHJG

with a fairly high performance graphics card. I know these riser cards are normally for server applications so I wasn't sure if there would be any issues.

Also, would using a riser card billed as Gen 1 PCI-e work out? Would it limit me to Gen 1 speeds or are Gen 1 and Gen 2 riser cards physically identical?

I'm thinking about designing a custom slimline enclosure using a Radeon 5770

Thanks

 

[MarkLuvsCS]

PCI-SIG announced the availability of the PCI Express Base 2.0 specification on 15 January 2007.[10] The PCIe 2.0 standard doubles the per-lane throughput from the PCIe 1.0 standard's 250 MB/s to 500 MB/s. This means a 32-lane PCI connector (x32) can support throughput up to 16 GB/s aggregate. The PCIe 2.0 standard uses a base clock speed of 5.0 GHz, while the first version operates at 2.5 GHz.

PCIe 2.0 motherboard slots are fully backward compatible with PCIe v1.x cards. PCIe 2.0 cards are also generally backward compatible with PCIe 1.x motherboards, using the available bandwidth of PCI Express 1.1. Overall, graphic cards or motherboards designed for v 2.0 will be able to work with the other being v 1.1 or v 1.0.

The PCI-SIG also said that PCIe 2.0 features improvements to the point-to-point data transfer protocol and its software architecture.[11]

In June 2007 Intel released the specification of the Intel P35 chipset which supports only PCIe 1.1, not PCIe 2.0.[12] Some people may be confused by the P35 block diagram which states the Intel P35 has a PCIe x16 graphics link (8 GB/s) and 6 PCIe x1 links (500 MB/s each).[13] For simple verification one can view the P965 block diagram which shows the same number of lanes and bandwidth but was released before PCIe 2.0 was finalized.[original research?] Intel's first PCIe 2.0 capable chipset was the X38 and boards began to ship from various vendors (Abit, Asus, Gigabyte) as of October 21, 2007.[14] AMD started supporting PCIe 2.0 with its AMD 700 chipset series and nVidia started with the MCP72.[15] The specification of the Intel P45 chipset includes PCIe 2.0.

Physically it should be identical and since the bus is backwards compatible it shouldn't matter. The bandwith from a single card shouldn't hinder performance.

http://www.hardocp.com/article/2010/08/16/sli_cfx_pcie_bandwidth_perf_x16x16_vs_x16x8/6

shows virtually zero difference between x8 and x16 so i imagine PCI v1 vs v2 would have minimal impact if the PCI-E v1 would be running x16.

 

[WhoBeDaPlaya]

shows virtually zero difference between x8 and x16 so i imagine PCI v1 vs v2 would have minimal impact if the PCI-E v1 would be running x16.

Even PCI-E v2 4x / PCI-E v1 8x doesn't impact performance too much (~5%).

 

[yottabit]

Thanks guys. Has anyone actually used one of this?

I'm worried about a riser such as this:
http://www.camera2000.com/en/pci-express-pci-e-16x-riser-card-extender-cable-1u-2u.html

Because I assume there must be some added latency from essentially doubling the wire length to the GFX card. Thoughts?

 

[deimos3428]

Because I assume there must be some added latency from essentially doubling the wire length to the GFX card. Thoughts?

You're right, but it's probably not significant. You're adding ~1 ns round-trip if I did the math right.

 

[PingSpike]

There isn't much information about these kinds of things out there, from when I was looking. However, I never found any examples of these kinds of things not working as expected so that is at least somewhat encouraging. My opinion is it will probably work fine. I've used some 1x to 16x converters and noted no problems outside of some performance loss from the reduced bandwidth. (expected)

I do see that the items are a lot cheaper then when I was looking.

 

[Yuriman]

I was looking into AGP risers years ago, and my reading then suggested that as long as the riser is short, you won't have problems. How short? I don't know.

That cable is almost 5 inches long, and if I remember, I was trying to find one that was <2 inches, but perhaps latency isn't an issue anymore?

Hope that helps.

 

[Throckmorton]

Are there cases with the slots aligned to match those risers?

 

[yottabit]

Are there cases with the slots aligned to match those risers?

Not many that I know of... Most are OEM cases like if you look at an IBM/Lenovo ThinkCenter or something like that, they'll usually have that style of riser in there. But most cases on Newegg and such rely on low profile cards.


An additional concern I have now is reading about the card specifications, Graphics cards may draw up to 75 W from the PCI express slot. Since the added cable will increase the electrical resistance, I worry. I guess there is no better way to find out than to try it though

I am planning to design a very slimline case using either a mATX or miniITX motherboard and discrete GPU. Should be fun

 

[darckhart]

I was able to use one like this very successfully:
http://cgi.ebay.com/nVidia-PCIe-x16-Wearout-Extender-Card-600-10247-0000-/230572412700

However, that longish ribbon one a few posts up did not work reliably for me. Upon booting, sometimes it would detect the video card, sometimes it would not.

 

[yottabit]

I was able to use one like this very successfully:
http://cgi.ebay.com/nVidia-PCIe-x16-Wearout-Extender-Card-600-10247-0000-/230572412700

However, that longish ribbon one a few posts up did not work reliably for me. Upon booting, sometimes it would detect the video card, sometimes it would not.

Thank you darckhart! That will save me the trouble of buying both of them then

 

[yottabit]

Update: bought a 1u riser and its working great with my 5770

Thanks!

 

[amtonio]

Update: bought a 1u riser and its working great with my 5770

Thanks!

wow,which one did you buy?

 

[PingSpike]

I just remembered back in the AGP days I saw a mod project where a guy made a PC that fit into a suitcase, basically a fat heavy laptop made with desktop parts. He ended up building his own cable extension for AGP from some kind of riser, wires and his own soldering skills so that he could change the orientation of the card to fit it in the suitcase.

 

[yottabit]

wow,which one did you buy?

I first used one of these StarTech 1U ones:
http://www.tigerdirect.com/applicati...7BBTkwCjCECjCE

Later switched to a slightly taller (1.5U ?) Riser I found on ebay because the 1U didn't quite raise the graphics card up enough to give adequate clearance for a dual slot card.

Also added a wearout extender because using the riser without one puts the tab from the metal bracket on the graphics card into the IO plate