Hello BOINC Community

I'm considering buying a refurbished desktop to dedicate to BOINC tasks. I'd like to buy a value GPU (eg; AMD 7770) to accelerate tasks. Its likely that said desktop will only have a PCIe 1 bus to equip the GPU.

My question is, how can I tell if any graphics card I buy will saturate such an interface? I understand that PCIe 1 handles 250MB/second/lane. Where can I find out how much bandwidth the graphics card requires?

If a 7770 saturates the available bus, I would prefer buy a cheaper GPU.

Regards
Albino

Check before you buy.



If you only have a PCIe x1 slot, it's likely to be the very short physical connector. Most GPUs will require the full x16 connector, even if they're running at a lower speed.

Thanks for your response Richard

I should have been clearer. My question relates the bandwidth requirement of the card itself.

The Radeon 7770 at my local etailer is a PCIe 3.0 model with x16 connector. I want to know if such a card would saturate a PCIe 1.0 x 16 connector (probably yes). If so, how could I determine bandwidth requirement for GPUs generally?

Josh

I looked into this and it seems that an x16 card won't physically fit into an x1 slot. There are some people out there on the internet that tell you to cut off the 'not needed' pins from the videocard (DON'T!), or to melt open the back of the PCIe x1 slot, so the x16 can fit (ALSO DON'T!).

But it's probably easier to go find something like this adapter, or just buy a new motherboard with one or more x16 slots. Depending on your budget, and don't forget to check which CPU is in there, you can buy e.g. a 3x PCIe x16 Asrock Z77 Extreme M4 for just AU$114.- (CPU - Supports 3rd and 2nd Generation Intel® Core™ i7 / i5 / i3 in LGA1155 Package)

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Hi Ageless

There seems to be some confusion about my question. I mustn't have explained properly.

The motherboard has a Gen1 PCIe x16 slots, so its not a problem of physical dimension.

What I want to know is, if I max out a given graphics card performing work for BOINC (or any application for that matter), how do I know what its interface bandwidth requirements are? I will compare this information against the available bandwidth from the PCI bus to see if I should get a better motherboard or buy a cheaper GPU.

Regards
Josh

The videocard itself always states what its maximum PCIe speed is. So in the case of the AMD 7770 you have an eye on, at Specifications it states PCI Express 3.0 x16 bus interface. PCIe 3.0 is backward compatible with PCIe 2.0 x16 slots.

But yes, since PCIe 1.0a only has a per-lane data rate of 250 MB/s and a transfer rate of 2.5 gigatransfers per second (GT/s), this card's 985 MB/s per lane and 8 GT/s bit rate will overwhelm the transfer of the slot. It may work, but it won't be pretty or fast.

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