Frequently Asked Questions (FAQs)

8 min read

This is a list of questions that are frequently being asked by people around FPGA community. If you have any questions that are not listed below, feel free to contact :

Q: How can I get the website updates?

By πŸ’Œ Suscribing to our mailinglist. And if you missed out on the previous newsletters, you can always read it on our πŸ‘‰Newsletter Archive Page!

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 license key? And how do I use it?

Currently, there are 3 license keys that use for running Digital Cruncher's bitstream. You can put the license key in license.txt inside ccminer folder that can be found in ⬇️Downloads page based on bitstream that you will use. Then run the file. Also there's the license key for running NextJTAG by NextDesignSolutions. You can buy it on πŸ›’FPGA Guide Shop.

Q: What is the most profitable bitstream for FPGA?

Check out our πŸ†Top Bitstreams Page. Updated regularly.

Q: Is there any quick calculator for showing ROI?

Yes! Can be downloaded here.

This quick calculator is an excel template which can be useful to show ROI. Enables you to enter the dates, values,and more. It's available bitstreams for BCU1525, VCU13, Xilinx Artex 7, and BlackMiner F1. All bitstreams are dated as per last recorded hash / value.

Thanks to for sharing it with the community.

Q: How should I build my water cooled rig?

Generally speaking, you should be using about 240mm worth of radiators per FPGA (350 W). Do not mix aluminum components with other metals in the same loop. Even ones with a zinc coating can degrade and begin galvanic corrosion in the absence of a powerful inhibitor in the coolant.

Q: How many watts does my PSU need to have?

You need a PSU that can push out at least 350W per VCU on the 12V rails. A high-quality PSU 1200W (like HP Server) is fine, but most generic 12/1300W only have 90-100A 12v - and can't handle the power on current onrush. The BCU is more forgiving on this than the VCU due to additional bulk capacitance on the 12v. Keep in mind that a 1300W PSU cannot generate 1300w on the 12V rail, 1300W is the power capacity across all voltage rails.

Also, make sure that you read the PSU rating and how many watts it is rated for. Some of those server PSUs are "1200W at 240V" but only 900W at 120V (or don't run on 120V at all). Ensure the unit you're grabbing will remain at the power rating you require on the voltage you can supply to it. Also give it a fan that blows into it on the breakout-board side, unless you open it and reverse the fan. They can get much warmer under load.

Q: How many BCU can be cooled by one radiator?

It depends on which type radiator that you use. We recommend using a copper/brass based radiator. That radiator can cool 2-3 BCUs running at 300W. So you'll need one radiator for two BCUs. And the better the fans you have, the better it cools your BCUs.

Q: Do I need an extra CPU cooler for my BTU9P?

The extra CPU cooler is not required. You can run most of the bitstreams available without an extra cooler on the backplate. You can add an additional cooler to the backplate. But FPGA is a very sensitive hardware, be careful when you apply the additional cooler, and make sure you understand which components should be cooled.

Q: Where can I buy a watercooling kit for my FPGA board?

You can buy it at πŸ›’ Shop. It's compatible with the BCU1525, CVP-13, BTU9P, XUPVV4-VU9, and MA-X1.

Q: What motherboard should I use?

As of right now, there are no bitstreams that require the full 16 lanes per FPGA or even more than 1x (What risers do right now). You can use any motherboard that you want, as long as they work with risers. Or check out our recommendation in πŸƒQuick Start Page.

"... If you want to future-proof your rigs to have support for x16 electrical and physical (directly inserting them into the motherboard) then you need to start looking at more expensive, beefier motherboards that support threadripper CPUs which have 60+4 PCIe lanes, the board would only allow you to run 3 boards at full x16 speeds, or up to 4-5 boards at 8x. I have not seen any boards that would let you fit more than 4 or 5 FPGAs." - Dream

Q: What CPU should I use?

"I strongly recommend using something better than a Celeron CPU to run more than 1-2 cards as you will probably overwhelm the CPU. A Celeron will work but with more cards, it will bottleneck your miners and you will see a noticeable hash rate decrease. Generally speaking, you should be pairing a maximum of 2 BCUs/VCUs per CPU Core (1 card/thread)." - Dream

Q: Why did the part number change from VCU 1525 to BCU 1525?

"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 BCU 1525 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: What is "the shell"?

"The shell that people are referring to is the ⛏ 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 VCU 1525 or BCU 1525 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 BCU 1525?

"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 πŸ›’" - Whitefire990

"Never, ever, have a DC1613A connected while running e.g. minerator... You might fry your board" - TheSeven

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

"The water block makes a huge difference on the VCU 1525, but a small difference on the BCU 1525. 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 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

Q: How hot Acorn can be run?

"80C is hot for Acorn CLE 215 and Acorn CLE 215+, 100C is hot for Acorn CLE 101" - GPUHoarder