Is bitcoin mining technology good enough for gpu rendering?

(BigLouis1971) #1

I have seen some bitcoin mining frames with 8 GPU capacity and they are able to install all those GPUs to fairly cheap motherboards for CPUs with 16 PCIe lanes. They use PCIe 1X to PCIe 16X adapters to install all those GPUs. According to what I learned from forums so far, I need a CPU with at least 28 or 40 PCIe lanes and at least a X99 chipset motherboard to install 3 or 4 GPUs respectevely for rendring effectively with GPUs. My question is, are those bitcoin mining rigs good enough for rendering? I guess not becasue those CPUs and motherboards don’t have enough PCIe lanes to keep good enough GPU performance, but I can be wrong.

Have anyone tried those rigs for rendering with Blender and post their experience? Thanks in advance.

(BeerBaron) #2

According to what I learned from forums so far, I need a CPU with at least 28 or 40 PCIe lanes and at least a X99 chipset motherboard to install 3 or 4 GPUs respectevely for rendring effectivelywith GPUs.

The way things are now, that’s not true at all. Almost all transfers to GPU memory happen at startup, so PCIe bandwidth does not affect rendering performance significantly.

In the future, if Cycles gets features to stream data (that doesn’t fit into GPU memory) from main memory during rendering, that situation may be different. In either case, for best performance, there should be as few PCIe transfers as possible, no matter how much PCIe bandwidth you have.

My question is, are those bitcoin mining rigs good enough for rendering? I guess not becasue those CPUs and motherboards don’t have enpugh PCIe lanes to keep good enough GPU performance, but I can be wrong.

Nobody uses GPUs for Bitcoin mining anymore. If you see a Bitcoin mining rig, it’s not a GPU rig (or it is very old) and it can only be used for Bitcoin (or related cryptocurrency).

If it really is a GPU mining rig (e.g. for Ethereum) look at which GPUs are on there, some of them may well be attractive for rendering.

(BigLouis1971) #3

Another question arouse. Can I install GPUs in the PCIe 1X slots with the help of those adapters and use them for rendering?

(BeerBaron) #4

That should work, as far as I’m aware.

(BigLouis1971) #5

In a few days I’ll get some of those adapters, install them to my PCIe 1X slots along with my GPUs, run the BMW benchmark and post my results. This is pretty good news for me because I was seriously thinking about getting some 4-way SLI capable hardware, but now I think it’ll not be necessary and I can spend the money in GPUs instead than new CPU, Mobo, RAM, case and PSU. The GTX 970s now cost about $200 used which I think is a nice value per dollar if you ask me and If I can install up to 5 of them in my present rig with no noticeable loss in performance due to bandwidth, then that’s very nice value for my money. What do you guys think?

(BeerBaron) #6

That would be interesting to see, but I think the 3.5GB of VRAM on the 970 are too low going forward.

(BigLouis1971) #7

What about the RX 580 and it’s 8GB of VRAM? How do they perform compared to the GTX 970 and GTX 1070 in Cycles and Luxrender?

(sundialsvc4) #8

The actual scam of Bitcoin is to persuade you spend thousands of Dollars(!) on a special-purpose piece of equipment that can do nothing else.

Always remember that Leland Stanford, and the other “Big Four” of railroad fame, got their original start by running hardware store in San Francisco, where they cheerfully sold mining equipment to hopefuls. (Other people made good money selling photos.)

Bitcoin is the same way. You don’t understand what “barter tokens” are, and you imagine that you’re going to get rich. Of course you do. They all do.

(Photox) #9

The OP never claimed he was going to, or was attempting to, “get rich.” He simply asked if a mining rig could also be used as a render rig. A regular motherboard can loaded up with GPUs and used for both. At this point in time it is true that your electricity costs will be higher than the amount of BC you can mine using it, but everyone knows that, it’s not some hidden fact or scam.

(BigLouis1971) #10

I received my cables a few days ago and did some tests. Since it was a temporary test I just put my tower in a vertical position, installed my GTX 1070 and GTX 970 in the PCI-E 2X and PCI-E 1x slots respectively with the ribbon cables and just placed my cards laying around without touching any circuits to avoid shortages. It took more than usual to boot into Windows 10, but finally the cards were recognized. I ran the classroom benchmark instead than the BMW with some modifications to the settings. Here are the times with the cards installed in different slots:

  1. both cards installed in PCI-E 8X slots: 36 seconds

  2. 1070 in 8X slot and 970 in 2X slot : 36 seconds

  3. 1070 in 2X slot and 970 in 1X slot: 44 seconds

  4. 1070 alone in 16X slot: 51 seconds

  5. 1070 alone in 8X slot: 52 seconds

  6. 1070 alone in 2X slot: 56 seconds

  7. 1070 slone in 1X slot: 61 seconds

A few facts worth to be mentioned are that there are no noticeable difference between 16X and 8X when rendering with the GTX 1070 alone. There’s 10% performance decreace between 16X and 2X and 20% between 16X and 1X. I have no 4X slot so I wasn’t able to mesure that.

I plan to get one of those risers that work with USB 3.0 cables because I think it’ll be easier to put the cards in a safe place with them instead than with the ribbons. I hope there’s no difference in performance between the ribbons and the risers.

I plan to build my own wooden box to be able to install the cards safely because right now I did my tests in a mid tower case with only 7 expansion slots and I wasn’t able even to use the third PCI-E 2X slot properly. Thanks for reading my post and I hope is useful for you.

(thomascheng) #11

Hey, how are things going with your rig? Can you do a test with a longer render scene. I’m wondering if the difference between 8x and 1x is due to the initial transfer speed to memory. Seems like render time isn’t affect at all by pci-E lane, except for initial loading time.

(D3Pixel) #12

Thanks for testing this, was just looking at all the Mining Rigs on ebay and wondered this exact question.

I too am interesting if the build time is a factor on 1x pci.

Checkout these motherboards, some support 19 GPU’s !!!

So, if I can put 6 x 1070 Ti’s (or others) into a mining rig and Cycles supports that many GPU’s then this could be a serious little render box.

That would be 14,592 cuda cores for £2,520 and a 1300w PSU to power it. Used purely as a render slave. It would seem lowest power+highest core count would be optimum balance, not sure about AMD cards.

Interesting stuff.

BigLouis1971, any updates?