Frequently Asked Questions (FAQs)

4 min read

Q: Where can I find bitstreams for my FPGA?

Currently, there are three developers that have released their bitstreams to the public. They are Whitefire, DigitalCruncher, and TheSeven. You can check more details and download their bitstreams here.

Q: Why did the part number change from VCU1525 to BCU1525?

"I want to be transparent that Xilinx has asked us to update the part number for the crypto-board to avoid causing issues with their data center customers because our prices are "too good." You're still getting the same (actually better, it has modifications for crypto)" - GPUHoarder

Q: What’s the difference between the BCU1525 and Acorn?

"They are both FPGAs, the acorn is just smaller in an M.2 form factor. You need custom miners to run both, but the acorn acts as an accelerator, not a standalone. The acorn only uses 15w of power and is aimed to help GPU miners get a performance boost in their existing rigs by offloading tasks the GPU can’t do very well and having the acorn compute those tasks instead. The larger, more expensive BCU 1525 is an FPGA that is essentially a GPU but with more hashing power." - Hacko

Q: How to use Lyra2z bitstream?

Lyra2z bitstream is in Website. To run it, you can use the minerator, and there's also the setup instruction.

Q: What is "the shell"?

"The shell that people are referring to is the Allmine shell which is a combination of bitstream/miner/web configurator which allow you to swap bitstreams by reconfiguring over PCIe. its an open dev environment where devs can port their bitstreams to and get fee collection, autotuning and PCIe drivers and stuff like that from the already built infrastructure. - Andreas"

Q: Can a VCU/BCU hash at x GH/s on ETH?

"Under no circumstances can a single VCU1525 or BCU1525 achieve anything above 150 MH/s, at best (even with light cache churn)." - OhGodAGirl

Q: Is mining with Lyra2z without cooling safe?

"yes, the lyra2z bitstream is safe. it will not cook your card even if you don't connect any cooling at all. it will not get any work done since its constantly hitting the shutoff threshold to prevent it from overheating." - Andreas

Q: Do I need a voltage controller like the DC1613A for my BCU1525?

"While you don't 'need' a DC1613A for a BCU, it still allows you to change some parameters in the regulators... Even with live voltage control enabled, personally I would insist on having a DC1613A. I use a DC1613A on my Bittware XUPVV4, even though it has live voltage control. Considering that you only need one DC1613A even for a dozen cards, the price is insignificant compared to the gain. You can buy the pre-modded one at" - Whitefire990

"Never, ever, have a DC1613A connected while running e.g. minerator" - TheSeven

*You might fry your board

Q: What can I expect if I order a water block for my BCU 1525?

"The water block makes a huge difference on the VCU1525, but a small difference on the BCU1525. I don't have access to the new BCU heat sink, but on the similar XBB1525 board, you would go from about 15.5GH/s (air) to about 16.7GH/s (water) - whitefire990"

*Actual performance numbers have not been tested or published (on the BCU).

Q: What is the most profitable bitstream for FPGA?

Check out our top-bitstream page. Updated regularly.

Q: What about overclocking in FPGA?

"Overclocking FPGAs is not really like overclocking GPUs. The FPGA doesn't have a fixed speed it can run but it instead depends on different properties of the bitstream. Overclocking the boards is more about how much over the power limit you can run the board without hurting it and how much heat you can dissipate from the FPGA and power components. If you are interested in extreme overclocking, you can try to use DC1613A, it allows you to change some parameters in the regulators. But use at your own risk." - Andreas