Finding the parts to build a PC

Hi All,

I’m new to the forums here, and i got interested in RISC-V by SiFive’s anouncement of “The first RISC-V PC” in October last year. So far i’ve been experimenting with RISC-V in Qemu, my favorite disto (Gentoo) seems to work nice. I’ve also tried a bit of assembly programming, and i mostly like it.

I’m now in the process of actually finding all the bits and pieces I need to actually build a PC based on the Unmatched. I’ll share my thoughts here, any feedback or additions are more than welcome. I actually wrote the posts with links to all the parts, bit the forums only allows me to use two links in a post. For now I removed them all, if needed i can post them later.

The first thing I need is a case. Because I understand the hardware is all new and a bit experimental I thought easy access to the hardware might be a good thing. That gave me these options:

  • Streacom BC1 Mini
  • Raijintek Paean M
  • Thermaltake core p1 tg

I like the BC1 Mini because it’s open and compact, unfortunately it’s quite hard to find a local reseller.

Assuming the BC1 Mini case, I need a SFF format PSU. The Corsair SF450 seems to be a high-quality option.

Video seems to be a difficult one. I don’t need anything special (usually the intel integrated graphics are more than enough). On the forums here i saw some posts about the Sapphire R5 230 card which seems to be a nice low cost option.

For storage i’ll go with the Samsung 970 EVO Plus 250GB specified in the GSG. I couldn’t find the actual meaning of the “Plus” in the name, does anyone know?

A desktop also needs sound :slight_smile: so I guess USB Audio is the only option, maybe with an adapter to fit the M.2 slot?
I did find some very-low cost (and presumably low quality) options and some expensive HiFi ones offering only audio output. Does anyone a know a decent quality USB audio device with audio in and out? (usually line out/headphones and mic.)

Last but not least, I’d like to replace the CPU fan with something passive, I hate fans :slight_smile: . Do we have any information on the power that needs to be dissipated? Note that using Gentoo means it will often be working at maximum load for hours when compiling updates.

So what are your plans? Do you have any suggestions for my ideas?

Thanks in advance!

Best regards.
Wesley

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No one has seen or tried the production hardware yet – not even I think SiFive employees.

I’ve posted about the Sapphire R5 230 card I have waiting. There is no guarantee that it works. I will of course post when I know.

Minimally, I believe you should be able to boot up and ssh into the board with just a ATX PSU, an SD card, and an ethernet cable.

The old HIFive Unleashed uses around 6W of power running at 1.5 GHz (for the whole board). I don’t expect the Unmatched will use more. It has a slightly more sophisticated CPU core design with two integer execution pipelines per core instead of one, which probably causes it to use a bit more power when loaded (I’d guess 20% more). But at the same time I believe the FU740 has some kind of energy saving mechanisms such as clock gating idle functional units. The FU540 has nothing like that.

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Only if you know or can guess the ethernet address. Otherwise you will need a microUSB cable for the serial console.

Thanks for your reply’s.

@bruce I am aware that the R5 230 is not confirmed to work, but it’s cheap, so if it doesn’t work it’s no big loss. The card listed in the GSG is waaay over-specced for what I need. And it has fans too … even more than one if I remember the image correctly.

Power consumption seems low enough to be able to be passively cooled. My current desktop has an Intel Celeron J1900 processor with a TDP of 10W which can be can be kept at ~60 degrees Celsius at full load with passive cooling.

With such modest power consumption the 450W PSU seems a bit too much (although it’s quite hard to find something lower).

@jimw i guess the initial (network) configuration via microUSB and after that ssh via ethernet would be the usual route for such a setup.

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@pa4wdh, For audio, I don’t see a reason why the HDMI or DisplayPort output from your video card would not work. My last 2 desktops running Gentoo were able to use such. The old one from NVIDIA video card, over HDMI. And my current one from AMD Ryzen with built in graphics over DisplayPort.

If you need to, their are some HDMI audio spliters. Some even transmit the audio out at that point as Bluetooth.

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Fortunately domestic routers invariably have a web interface that will tell you the IP and MAC of connected clients.

Thanks for your suggestion. I am aware that HDMI can do audio too, I wasn’t aware DP also did that. As far as I know (please correct me if I’m wrong) this only gives me audio output, not input, so I’d still need a solution for that.

@pa4wdh, Glad I could help.

No, neither HDMI nor DisplayPort do audio in. (As far as I know.) So yes, a USB dongle with jack for microphone, or even full stereo headset with microphone input would be needed if you want audio in.

Note that some HDMI to DisplayPort convertors also pass the audio through. I use a Mini-DisplayPort on my home monitor for my laptop, which has HDMI output. The audio out worked last time I checked.

The sound “issue” has been solved in an unexpected way. I came across an Asus Xonar U7, i’ve tested it on my current hardware to verify it works, so it’s a perfect candidate to test with the Unmatched.

The only doubt i have about my parts list is the PSU. The corsair SF450 seems a bit over-done, does anyone know a more appropriate one? So far i’ve found PSU’s upto 150W (like the PicoPSU), one step up from there brings me to 450W models. Something in between those numbers would be nice :slight_smile:

Today I tried to pre-order an Unmatched at Mouser, their site currently says they can’t sell in my country (The Netherlands). It didn’t say that before, is there a problem?

I believe it is a temporary paperwork issue that will be fixed before the boards ship.

Thanks for your answer Jim, I’ll just wait for the paperwork to be fixed.

I found a passively cooled AMD Radeon R5 230 which I plan to put in a Fractal Design 202 case - the GPU compartment is really oversized but the case looks good. I also got a SilverStone ST45SF-G PSU to go along - really is not needed, but as @pa4wdh rightly points out, I just couldnt find any less powerful models.

Minimally, I believe you should be able to boot up and ssh into the board with just a ATX PSU, an SD card, and an ethernet cable.

Does the HIFive Unmatched come with a SD card reader? I got a M2 SSD, as that was the only connector I found info about.

Edit: The SSD I got is a Samsung 970 EVO Plus 250 GB.

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Yes.

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Can you give an estimation on when this is expected to be fixed? Mouser still says I can’t order because of some restriction.

I’m not directly involved with the unmatched project, and even if I was I doubt that we can give a firm date as this is mostly outside our control. The EU won’t let Mouser accept pre-orders until the import paperwork is done. And apparently this is an EU policy change as Mouser could accept pre-orders before. This requires working with testing labs, lawyers, and bureacrats. We can’t predict when this work will be done. We don’t expect any problems, and do expect this will be done before the boards will ship.

Essentially, we need this
https://en.wikipedia.org/wiki/CE_marking
or some subset of it.

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Thanks for your answer @jimw. I understand you can’t give an exact date for this, such paperwork can be a long process. I hoped you could say if it’s more likely to be weeks or months or even more.
I’m aware of the CE marking, it’s on about every product I have over here :slight_smile:.

My main problem is that I need some other new hardware (as discussed in this topic), and frankly, without the mainboard its pretty useless to order them. So if there’s any risk the board might not be able to delivered in the EU at all it’s better to wait to order the rest of the stuff until I’m sure. Knowing it’s “just” the CE mark is good, given the overwhelming number of products that have it I guess the risk of not being able to comply it quite small.

In the interim, perhaps you could check out the Microchip Icicle board. It uses SiFive RISC-V cores. I was able to get Debian sid running on it last night.

$ cat /proc/cpuinfo 
processor	: 0
hart		: 1
isa		: rv64imafdc
mmu		: sv39
uarch		: sifive,rocket0
...
[4x processors]

Unmatched vs Icicle

CPU Speed: ~4x (?? 2.5x in clock speed, ~1.6 in IPC)
RAM: 8x (16 GB vs 2 GB)
“Disk” speed: 20x (?? eMMC vs M.2 SSD)
Price: 1.33x

The Icicle does have two large advantages: a large FPGA to play with, if you’re into that, and it’s shipping now.

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Thanks for your suggestion on the Microchip Icicle board @forksand (and thanks @bruce for the diff). From the specs I think it’s not the right thing for me, I have no intention to do FPGA stuff, which I think is quite a bit part of it’s price :slight_smile:. Besides that, i’ll be running Gentoo, so i’ll prefer the faster processor and more memory of the Unmatched board.

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