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I am wondering. To make a rig you usually need to get a motherboard, RAM, CPU, and a hard drive among a strong PSU and the GPU's and PCIe risers

But I could possibly save a lot on the motherboard, CPU, RAM, and HDD by just picking up used old HP or Dell PC's which have a few PCIe slots.

Is there a specific problem with cheap motherboards and functionality? First thing I can think of is older motherboards and CPU's being limited by bus speeds when handling multiple GPU's

I don't think you'll have problems with speed, but you may have issues with configuration.  Some OEM bioses have artificial limits to create segmentation of markets (high end boards limited to be lower performing models). Also, you'll most likely have to use risers, as most OEM boards will most likely only have one x16 slot, and maybe one or two x1 slots.

It's worth a shot though. You can get fairly capable returns for $200 or less. Just make sure you swap out to a good PSU.

You got me curious...  :)

I found this refurb on newegg:

http://www.newegg.com/Product/Product.aspx?Item=N82E16883162047 (http://www.newegg.com/Product/Product.aspx?Item=N82E16883162047)

You'd have to remove the motherboard from the case to fit two GPUs.  It has one x16 and one x4 (both are physically x16 connectors).  If you were up for a riser, you could possibly also use the x1 slot.  So, three cards max.

As stated before, you'd need a different PSU.

Not a bad deal, considering you get all components, and the OS.

Don't touch those big box store computers.

The bios can be limited, required a specialized computer supply to power on and do weird things that an oem intel or other similar board won't have problems with.  It might lead you to going nuts trying to figure out the problems.

What I do is buy LGA 775 Intel boards on ebay, DDR 2 ram and core 2 duos.  You can find a mobo that will work with 3 gpus for about $30, cpu $5, ram ~$20 4GB, and millions of HDDS to find.  I run the system headless with team viewer but I don't even bother to login as long the rig is mining.  You can find some older mobo that will take 5 gpus but they are more expensive and I can basically build another system for the price difference.

Once you find a configuration that works, stick with it.  Also you will be less efficient with smaller rigs as each system base will consume about 50 watts but the price to get a 3 card rig ready to rock will be very low.

Old stuff is slow compared to new stuff. You'd "save" a lot, but you'd also make next to nothing.

also i highly doubt that there is something from the past that come even close to the h81 pro btc as a MB

Well, I could get an old HP to mine with 3 GPU's and I have an extra PSU that can handle 3 cards that are optimized for efficieny, but certainly not 3 cards pushed for gaming OC's with no regards for efficiency.

1 PCIe x16, 2 PCIe x1 slots

I could swap the wireless cards between the regular PCI card on my main computer and the PCIe card on the HP. Also that regular PCI wireless card on my main computer would interfere with running SLI anyway so I would have to swap the wireless cards if I ever wanted to do 2 GPU's in my main computer


For most instances. People would be needing to get a PSU for this idea. In my case I got one old PSU to do this right now. So it would be simple as just buying 3 GPU's and powered risers. This PSU would not be able to power a dedicated 6 GPU rig. So this is one exception where the investment for the rig is nothing more than the GPU's and risers

Which means you don't have a PSU that will do you any good in the current scheme of things.


You've got to understand 1 thing:

Many people have gotten  150 watt TDP cards to mine at under 110 watts, sometimes 90. That is different from someone running 3 cards all of them overclocked and pushing the full TDP or above.  I'm holding my stance that this PSU would be fully capable of running 3x well tweaked RX 480's well within the ideal PSU utilization range and I could be even safer by using RX 470's or GTX 1060's which have lower power draws to account for the PSU degradation from its previous use

The real question is would an LGA 775 based motherboard and CPU from 2009 actually hold back GPU performance?

I can look up the very CPU and people still game on it although overclocked now. Despite proper GHz there is some amount of bottleneck present so there may be some diminished hashing. I could plug up my 1070 into it and see for myself if the hash rate is the same.

As someone that swings 60TH/s worth of SHA256 ASIC miners around for fun (as long as I make my BTC quota, the rest is all fun), I can tell you that there is no coin worth mining that you can mine with all 3 cards using one 150w PSU.

You cannot pull the hashrate to pay for a cup of coffee! :-\

Repeating incorrect information does not make it correct.

The CPU, RAM and PCIe version are trivial for GPU mining. It's all about the GPUs and the PSU. I've got a PentiumD 32 bit,
4 GB RAM mining with 2 GPUs. The amount of RAM could become an issue with certain algos and multiple cards.

I say it's a good plan. If you rebuilding from scratch try to get the latest BIOS, get a good PSU, max out the RAM, a few GPUs,
powered risers and you're good to go. Always use powered risers even on the x16 slot to avoid stressing the old MB.

All you need is pcie slots. S775 works just fine, next to me is sitting one mb from some old office pc, with only two pcie slots it is doing pretty well. 105MH dagger + 2000MH sc.

-edit-

I think I payed 30€ for that mb+e8400+8gb set last winter.

I did this when I started mining Bitcoin back in the day. I took my existing system as well as 2 others that had been sitting in a closet. Sure it wasnt the most efficient or dense setup but it was cheap as I already had the parts except for the GPUs and even those I picked up on ebay for less than $100 each at the time.

Buying older tech for this purpose may or may not work, depends on what it is and price but using old tech you already own does work!

You're as dense as he is!


His whole concept (and what I'm telling him will not work) is running 3 GPUs of some old, beat up 150w PSU that he already has!
He doesn't believe he needs a better/new PSU!


If you're going to try to break down what I write, at least read it first!

I think op has an extra psu.

But profitable mining rig with 150w psu? Hmmm... 3x750ti on x.. or s.. could do it.

I did, try again. OP never mentioned the capacity of his existing PSU but he said it could handle 3  150 watt cards. You're assuming he's
an idiot and doesn't know anything about power. From reading his post I sensed he understood the power issue but I reitreated it anyway
in a non-insulting way.

Not only is your advice probably bad you're insulting when you give it.

Yes, my bad, I missed finding the one 2009 HP LGA 775 tower that did have a 250-watt ATX Power Supply (which still wouldn't support 3 frigging cards).  :-\


You're right, we should tell all of the n00bs to go ahead and mine with weak junk; that way when they can't make 1BTC in a years time, we can  ;D at them for being "stupid n00bs"!
Dafuq was I thinking in trying to get him to do something that might have some change of profitability? ???

As a general rule, "old" Dell/HP/etc systems will have ONE PCI-E slot if they have any at all.
I looked at that seriously before my move, decided there wasn't enough savings to justify the major increase in SYSTEM power used over 2+ card rigs.

 The system OP specified however might be worth looking at - but you're basically paying $200 for a CPU/RAM/HD/Motherboard as the rest of that system is UNUSABLE, so the savings if any aren't all THAT great.

 The spacing on the pair of PCI-E 16x cards IS nice for a dual-card rig, but you'll HAVE to use at least 2 risers to be able to use the 1x slot.


 The "old stuff is slow" issue DOESN'T EXIST - the only thing you're using the CPU for is DAG file creation and data transfer - and IME even old AMD Semperon64 2800+ is more than enough to keep up with even mid-to-high-range cards (I've got a R9 280X in one of my Semperon64 2800+ based systems hashing quite nicely in the 20MH/s+ range).


 My "big rig" ran 3x R9 390s at 90MH/s using a SINGLE Semperon 145 - and it wasn't loading that CPU much at all EXCEPT during DAG file creation.



 OP SPECIFIED he had an extra PS to replace the one in that machine.
 He didn't specify the wattage rating though.

Hp elite 7100 mt staring at me doing nothing, 300w psu + w7 license. Cost 0€.

He said he had another PSU that could handle 3 GPUs. It's ironic that you accused me of not reading and it's you that
is clueless.

I'll assume you had good intentions to start but your reply was caustic and over-emphasized suggesting forfcefullness
with a touch of anger. I don't care about you but I care about bad advice so I spoke up. Your reply to me degraded to name calling
while still completely missing the point. And you still haven't clued in. Maybe I should use bold text so you'll see it.

I found the OP's initial question well researched, much better than most newbie questions, and he didn't deserve your type of response.
Even if it was a dumb question you aren't helping by belittling him for beeing a noob.

I'm done with you and your need to feel important. Flame away you can have the last word.

I was not talking about a standard HP PSU, I mean I have a real PSU just sitting around that is over 600 watts. It's wattage is some odd number rather than one of the convenient rounded ones.

You went on to mention 150w PSU multiple times and even called someone else dense. For the record this HP I can use has 3 PCIe slots total

To use an old computer that has little selling value was the main idea of the thread. For just one build I have a PSU but I would need to buy PSU's for other builds otherwise and so would anybody else who was buying old computers for mining.

I suggest you go with Nvidia, they are more power efficient. 600W isn't enough for 3 decent cards. Two bigger cards would
be better. Make sure you have enough PCIe power connectors on the PSU and don't rely on Molex to PCIe adapters unless
you've calculated your power requirements precisely, with enough headroom to OC if that is part of your plan. Two 1060s
would probably work well, two 1070s is probably too much.

http://powersupplycalculator.net/

Using power supply calculator, it estimates 530 watts load with GTX 960's since there are no 1060's on there yet, same TDP. The load would exclude the CPU that is a 95 watt TDP. It did recommend a PSU at 731 watts. That would be 72% load on the PSU, where most recommendations are to not exceed 80%. Looking more closely I would be exceeding 80% with the PSU without even rounding down the PSU to account for degredation. Guess I failed to simply eye the wattage without math.

Running 3 GPU's pushing 90 watts each and removing the CPU load wattage would work. But this would assume that rig remains dedicated to Ethereum lets say and I stay away from dual mining. Another option is if I do some 2 PSU setup where the basic HP PSU powers the mobo, CPU, HDD, and fans while this 600 PSU covers just the GPU's (including PCIe powered risers)

If you go with 2 PSUs you should make sure to use powered risers in all slots, including the x16. There may be other issues
but I'll let someone who's done it comment further.

LGA 775 mobo will not hold back mining performance, I currently use lga 775 and core 2 duos for my mining rigs.  I also game on a lga 775 quadcore machine that is stock clocks and I really don't notice a bottle neck, well the games have stunning visuals and great fps.  I have 2 cards in a lga 775 "daily driver" machine, I keep one mining and the other is for gaming..still works great.

Don't listen to some of these people, they just have the idea stuck in their heads that old hardware is junk.  Not true.

For mining the computer cpu does NOT do the work, the gpu does all the hard work and the main system will just be chilling out waiting to send a little data packet to the pool when it finds a share. 

The PSU is the Corsair HX620w

It only has 2 PCIe 6+2 cables.

Besides GPU's the only investment is the PCIe risers and a workbench or materials to make a custom one. Only other thing I would have done with this HP was dedicate it to lower end requirement games with my old GPU in it to save storage space and registry clutter on my main computer. The HP locked bios holds it back from performing well as others still running this. It's why I would rather buy someones old computer on reddit hardware swap for low end games instead and turn this into a miner.

I won't be able to buy GPU's until September so I can decide later what to do with this


The CPU in this HP is a Q6600, 2.4 ghz quad core. I've looked it up before. Running with good GPU's it loses 10 fps on newer games compared to people with the same GPU on i5 and i7's even though the GHz is met. It's usable of course and running a good GPU will still play smoothly but the legacy is ceeping up

 Not on Ethereum mining - RX470/RX480 are a TOSSUP with the best efficiency out of any NVidia cards to date, but cost a LOT less per MH.

 600 is viable for 3 of those cards and a low-power rest-of-the-rig, if it's a HIGH QUALITY 600+ (Seasonic X-series 650 I'd be VERY comfortable with running that sort of a rig).

 Corsair 620 should be PLENTY for the 2 cards it CAN power and saves the cost and potential problems with risers.


 Q6600 is SEVERE overkill for running a mining machine, as any quad-core CPU (except perhaps an ARM from a smartphone) would be.