“Frequently asked questions” on the latest article…

Wow – and I thought the original phi mining article 8×7220 Phi System had gotten a lot of replies… man, was I wrong: the latest article on mining with the Asrock Rack 4×7210 system got a solid two thousand reads in the first 24 hours. Amazing.

Anyway – there were lots of questions on these systems (as well as on the Exxact system I mentioned earlier), and I’ll try to answer them all. I’ll try to answer every email I’m getting; but still, some questions seem to be recurring more often than others, and for those I think (hope?) it’ll be easier if I just put them onto the blog itself. I’ll start today with a two or three key ones, and will update this page (ie, not post a new one every time) as I get to it…. bear with me; I can only type so fast

Q: What is the wall power draw on those systems?

Probably the most asked question, and about an hour ago I decided it’s quicker to just drive to home depot and get a new Watt-meter than trying to reply to several emails (unfortunately I apparently fried my original one when I put it behind that 24kH monster machine I described earlier …. not a good idea).

Now with that brand new gadget, here’s what I got: My Asrock Rack 4×7210 system pulls pretty much 1300-1350W from the wall (on 110V, will update with 210 once I move it to my cohosting site). Of course that is under full load:

The 7210s have a TDP of 215W, so seems the rest of the system is pulling an additional 500Ws on top of that – way more than I would have expected, but still… 1.3KW for 11KH/s isn’t bad at all (that’s what my average GPU mining rig pulls as well, with significantly less output). The 7250s will likely pull more, but don’t have any asrack ones yet.

In my Exxact 4×7250 System I’m pulling more, apparently something around 1550W:

Note that is with the DIMMs and disks removed (see next post to come), but I doubt that’ll add more. Now why this pulls 200Ws more than the other one I don’t know – the TDP difference between 7210s (215W) and 7250s (250W) should only account for 140Ws, not 200… but then, I have them on 110Vs, which is where the PSUs won’t be at their utmost efficiency.

Q: Where can I get those systems?

Right now there’s two confirmed sources that I have used myself: one is Exxact Corp; the other is Asrock Rack. In particular the ~$3k system that the last post was about is from Asrock Rack.

For those that asked where to find the web page to order those from: Such a page does not exist (yet), but you can send an email to mining_phi@asrockrack.com . Note they “apparently” got quite some interest recently (wonder where this was coming from 🙂 ), so they may be short on stock.

In addition to Asrock and Exxact, you may also be able to get some such systems directly from Intel. I’ll post more when something on that front materializes more clearly, but at least if you want to buy more than just one or two systems I’m sure somebody would like to talk you (and I’d be happy to make the contact). Full disclosure: As my “About” page states I do actually work for Intel in my day job, but in a totally different capacity… (yes, “interesting” situation indeed, tell me about it).

Q: Why do some systems perform better than others?

As mentioned in an earlier post the default BIOS that these systems originally came with wasn’t optimal for the MCDRAM, but that can be fixed by using the right BIOS. Asrock Rack already found “the right” one; I’ll post it as soon as I receive it myself. Of course I also asked Exxact for one, but no reply yet (I only asked last night).

I sincerely hope Asrock will automatically put the right one onto future systems (in fact I’m 90+% sure they will), but jsut in case: you might want to tell them what the system is for, and ask if it has the right BIOS… just in case.

In addition, there also seems to be some OS influence as well – doesn’t make the slightest sense to me, but it seems Ubuntu can be up to 10% faster than CentOS – not sure if that’ll still be the case after the BIOS update, but at least for the old BIOS that difference has been confirmed by multiple users (as well as myself).

Q: Are those co-processors / GPUs / PCI cards ?

No. The x200 “Knights Landing” series (and now the x205 “Knights Mill” ones as well) are all “bootable” processors. You can get them in workstation form factor as well (e.g., from Colfax: http://dap.xeonphi.com/), but primarily they’re intended for High-Performance-Computing(HPC) / Supercomputing (e.g., the Stampede supercomputer has 6,400 of those Phis!), so their “natural habitat” is in rack-mount servers (e.g., in a 2U rackmount form factor). Either way, they are the “main CPUs” that go right onto the server motherboard. The big upside of this is that it’s so much easier to go “at scale” – find a co-location, pay them for their space and power, and just rack them up….

Note there are also a few isolated prototypes of PCI cards out in the wild (the so-called 7220s and 7240s), but this is a different discussion – and since they’re not freely available, anyway, please ignore them for now.

Q: What else do I need for this build ?

Well, that’s an almost trivial one: Nothing.

Though it’s significantly less fun than a “real” build (such as the one in my post with 7220 cards – that was fun!) these are ready-to-go rackmount systems. For the Exxact system the system comes with memory, disks, and OPA cards (none of which you actually need :-/); you can install linux on the disks, and run it, or take out the disks and use a pre-built bootable USB stick (will write more on that in a separate post).

The Asrock Rack system is a “barebone” system with just the chassis, PSU, and CPU – you don’t need either memory or disks, but you obviously do need something to boot off, so what I did is create myself a bootable USB stick with a linux distribution (and lukminer preinstalled in the boot script). So you do need those USB boot sticks (or to plug in your own disks – newegg has refurbished barracudas for $10 a pop!); but other than that it’s ready to go.

Be warned though they are not exactly quiet – they’re intended for data centers, not for “under the desk”, or “next to my TV”.

Q: Now why are the Asrock Systems so cheap?

Now that is an interesting question ;-). According to ark.intel.com the list price for 7210s is indeed around $1,900 per 7210; so one’d expect a four-node system to cost at least $8k just for the CPUs. However, there currently “seems” to be an active promotion going on where the “older” x200s (7210, 7250, etc) are availalable for a “lower” price – that may or may not be related to the fact that the newer x205 “Knights Mill” generation of the Phis is now out, but whatever it may be – right now they are quite steeply discounted. Asrock Rack (or Intel?) may or may not be able to tell you more about that… I can’t.

Note, of course, that if that is a special pricing promo it may or may not disappear at some point in time. Again, Asrock – or your favorite Intel distributor – may or may not know more.

Q: What miner are you using to get this performance?

Well – since this is the “lukMiner” blog you may not be surprised that I use the “lukMiner” miner :-). Pre-built binaries for the phis are available via this link ; and yes, I do take a developer share, so of course, I’m heavily biased towards these systems – I do not get any commissions from either Asrock, Exxact, Intel, or whoever (which is doubly weird because I work for Intel in my day job, in a totally different capacity!?) … but I do get a share if you guys are using lukMiner to mine on them. On the upside: That means I have a very high incentive to make it even better and even faster, and to also look into other coins….

Q: What coins is this for?

This can also be googled on the lukMiner google site, but just to mention it here as well: Currently lukMiner supports only cryptonight (monero, bytecoin, electroneum, sumo, …) and cryptonight light (aeon) coins.

As to other coins: Since the Phis are regular Intel CPUs you can, in theory, also run whatever other miner code you want to run… but be warned: The MCDRAM and the lots of cores will help, but unless a given code has been specifically optimized for the Phis you may not get the same profitability.

I myself am currently already working on a phi-optimized Ether miner, which of course would be a much “bigger” thing than just cryptonight (ether market cap is $85 billion, criptonight is 3.5 :-/)…. but that’s not ready yet. MCDRAM should help a lot – my current code makes 12ish MH/s and doesn’t even use a quarter of the MCDRAM bandwidth yet … but again, that’ll require some more work to look into. And of course, I’ll certainly post it if I get it running.

What performance should I expect for hardware XYZ?

I created a page on the google lukMiner site where I list – and continuously update – performance data for various platforms.

Can I also use the previous-generation 7120s, 5110s, etc?

Well, yes, lukMiner supports it …. but it’ll be significantly less profitable, to the degree that I’d advise against buying any of those. An overview of expected performance can be found on the respective lukMiner google site… do your math.

As mentioned in the beginning I’ll keep on adding more questions&answers to the bottom of this page, but at least for now I’ll have to go back to looking after my machines …

As such: Happy mining!