Radeon VII @ newegg for 500 dollars US on 11-27

[ewmayer]

Originally Posted by Prime95

Three cards in an ATX will run pretty (very?) hot. I do recommend a cheap open-air type mining rig ($20 - $25) unless you have cats or small kids that might injure themselves in the fans or exposed circuitry.

Yes, my current ATX-with-side-panel-removed will likely not cut it with 3 cards blasting away. My sister's nephews are 11 so understand "keep hands away", only potential issue is their oh-so-energetic 4-month-old German shepherd, but I would probably rig up some kind of simple window-mesh-based screen box for the system.

No radio-interference issues in our household, have never noticed any weirdness with our broadband WiFi related to the ATX system, but Phil's suggestion is certainly a good one for folks who need a full case for whatever reason.

So a small mining rig seems in order - do those take ATX-format mobos? Next issue is the cheapest reasonable-quality cpu+mobo combo which can accommodate 3 Radeon VIIs. Again, if the overall setup leaves enough wattage headroom to do some added crunching on the CPU great, but that is entirely optional. Suggestions welcome!

[Prime95]

Yes, mining rigs take ATX mobos.

I'm using some cheap Haswell-era mobos with only two full size PCIE 3.0 slots and two x1 slots. There are cheap x1 to x16 converters available. In fact, I only use one of the full sized slots on the mobo, preferring to use the x1 to x16 convrters to mount the GPUs far apart.


Another issue might be air conditioning. If your room/house does not have good air flow you might create an unbearably hot spot.

[ewmayer]

Originally Posted by Prime95

Yes, mining rigs take ATX mobos.

I'm using some cheap Haswell-era mobos with only two full size PCIE 3.0 slots and two x1 slots. There are cheap x1 to x16 converters available. In fact, I only use one of the full sized slots on the mobo, preferring to use the x1 to x16 convrters to mount the GPUs far apart.

Another issue might be air conditioning. If your room/house does not have good air flow you might create an unbearably hot spot.

Ooh, I like the first suggestion - so this seems the perfect opportunity for a fellow GIMPSer looking to upgrade their cpu to sell me their old cpu+mobo+mem combo fitting the above description for some agreed-upon price. Xyzzy just e-mailed me to effect of "i wish i had known, i would have given you the cpu i just gave away" - but I'm perfectly willing to pay cold hard cash to incentivze things.

Re. A/C, my apartment has both AC and good airflow - I usually use a fan pointing at my work desk on warm afternoons until interior temps get close to 80F, at which point the AC comes on. I have the open side of my current ATX-case cpu+gpu system facing said fan, that knocks ~5C off the Radeon VII temperature when turned on. Should be even more effective using an open-air rig.

[PhilF]

Originally Posted by ewmayer

Ooh, I like the first suggestion - so this seems the perfect opportunity for a fellow GIMPSer looking to upgrade their cpu to sell me their old cpu+mobo+mem combo fitting the above description for some agreed-upon price.

I use something even older.

I use a Haswell era motherboard also, but it has only 2 PCIe-16 slots, with only one of them a V2.0 (there's no 3.0 slots at all).

Going from an i7-4790 3.2 Ghz rig, Radeon VII in a PCIe 3.0 slot, to one of these ancient motherboards with a Core 2 Quad 9550S 2.83 Ghz CPU, with the GPU in a V2.0 slot, cost me only 5 us per iteration. Plus, the 9550S runs really cool since it is a 65W part (the S designation is important, otherwise it is a 95W part).

CPUs, motherboards, and RAM that old can be had really cheap. I think I have an 8200S and some DDR2 memory I can send you if you come up with a motherboard for them.
-Phil

[ewmayer]

@Phil: I'd really like to make full use of the 850W PS I bought by driving 3 Radeon VIIs - I suppose 4 might just be possible, but at that point you'd be having to underclock sclk enough that it would like be substantially less throughput than 4/3x that of 3 cards running at a higher sclk setting - so will be looking for something like George suggested, just with a view to fully populating the PCI slots (one GPU per pci3.0, thrid one using the two lesser pci 1x buses ganged together).

But I'm sure someone looking to buy their first Radeon VII would be happy to take you up on your kind offer!

By way of first-search-attempt, just looking at items under "AMD Computer Motherboard & CPU Combos" on ebay, which of the following have the needed set of PCI slots and provide good value for the money?

https://www.ebay.com/itm/Gigabyte-AB...MAAOSwCf5ec78w

https://www.ebay.com/itm/Combo-MB-CP...QAAOSwEwpedWTO

https://www.ebay.com/itm/ASUA-ROG-Cr...4AAOSwqSteaFnT

[Prime95]

Something weird happens when adding the 4th GPU. All of a sudden your CPU cores are pegged at 100% utilization. That is, it switches to polling.

Given the choice, I'd go with PCIE 3.0. AMD documentation says it does atomics better with 3.0, but I don't know if that is true. Also, I've seen occasional slowdowns (say 8 or 10%) running 2 instances. This has always happened on the 2.0 slots but that could well be a coincidence since I have more 2.0 slots than 3.0 slots.

[kriesel]

Originally Posted by ewmayer

I would probably rig up some kind of simple window-mesh-based screen box for the system.
...
So a small mining rig seems in order - do those take ATX-format mobos? Next issue is the cheapest reasonable-quality cpu+mobo combo which can accommodate 3 Radeon VIIs. Again, if the overall setup leaves enough wattage headroom to do some added crunching on the CPU great, but that is entirely optional. Suggestions welcome!

"Hardware cloth"; stout screen with ~1cm aperture size.
I like my Asrock H81 Pro BTC. Designed for 6-slot mining. A spare PCIe or two can be useful for diagnostics. 2 DIMM slots that take up to 8GB DDR3 each. An i7-4790K is economical. Has onboard VGA that still works with gpus installed. Because of geometry of gpus and the frame, I'm using the x16 with a x1 to x16 extender. I have 5 gpus on this. It's enough to run multiple TF on each gpu and still throw 4 HT cores at prime95 (8.3ms/iter on 83M PRPDC) and be responsive via remote desktop; 5GB ram occupied, 11 available. I had a Radeon VII on it for a while.
https://www.asrock.com/mb/Intel/H81%20Pro%20BTC/

C:\Windows\system32>"c:\Program Files\NVIDIA Corporation\NVSMI\nvidia-smi.exe"
Sat Mar 21 07:57:51 2020
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 442.19       Driver Version: 442.19       CUDA Version: 10.2     |
|-------------------------------+----------------------+----------------------+
| GPU  Name            TCC/WDDM | Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  GeForce GTX 1650   WDDM  | 00000000:01:00.0 Off |                  N/A |
| 68%   61C    P0    65W /  75W |    796MiB /  4096MiB |    100%      Default |
+-------------------------------+----------------------+----------------------+
|   1  GeForce GTX 1650   WDDM  | 00000000:03:00.0 Off |                  N/A |
| 58%   67C    P0    70W /  85W |    796MiB /  4096MiB |    100%      Default |
+-------------------------------+----------------------+----------------------+
|   2  Quadro K4000       WDDM  | 00000000:04:00.0 Off |                  N/A |
| 33%   62C    P0    46W /  87W |    407MiB /  3072MiB |    100%      Default |
+-------------------------------+----------------------+----------------------+
|   3  GeForce GTX 1650   WDDM  | 00000000:05:00.0 Off |                  N/A |
| 65%   78C    P0    67W /  75W |    469MiB /  4096MiB |    100%      Default |
+-------------------------------+----------------------+----------------------+
|   4  GeForce RTX 208... WDDM  | 00000000:06:00.0 Off |                  N/A |
| 71%   76C    P2   247W / 250W |   1371MiB /  8192MiB |    100%      Default |
+-------------------------------+----------------------+----------------------+

+-----------------------------------------------------------------------------+
| Processes:                                                       GPU Memory |
|  GPU       PID   Type   Process name                             Usage      |
|=============================================================================|
|    0      4080      C   ...uments\d1 mfaktc\mfaktc-2047-win-64.exe N/A      |
|    0      5664      C   ...ents\d1 mfaktc\2\mfaktc-2047-win-64.exe N/A      |
|    1      4108      C   ...uments\d2 mfaktc\mfaktc-2047-win-64.exe N/A      |
|    1      6532      C   ...ents\d2 mfaktc\2\mfaktc-2047-win-64.exe N/A      |
|    2      1784      C   ...s\d4 mfaktc\2\mfaktc-more-cuda80-64.exe N/A      |
|    2      6552      C   ...nts\d4 mfaktc\mfaktc-more-cuda80-64.exe N/A      |
|    3      6504      C   ...ments\mmff-gtx1650\mmff-win-64_2047.exe N/A      |
|    4      2128      C   ...uments\d0 mfaktc\mfaktc-2047-win-64.exe N/A      |
|    4      5024      C   ...ents\d0 mfaktc\2\mfaktc-2047-win-64.exe N/A      |
|    4      5652      C   ...ents\d0 mfaktc\3\mfaktc-2047-win-64.exe N/A      |
+-----------------------------------------------------------------------------+

[ewmayer]

Originally Posted by kriesel

"Hardware cloth"; stout screen with ~1cm aperture size.
I like my Asrock H81 Pro BTC. Designed for 6-slot mining. A spare PCIe or two can be useful for diagnostics. 2 DIMM slots that take up to 8GB DDR3 each. An i7-4790K is economical. Has onboard VGA that still works with gpus installed. Because of geometry of gpus and the frame, I'm using the x16 with a x1 to x16 extender. I have 5 gpus on this. It's enough to run multiple TF on each gpu and still throw 4 HT cores at prime95 (8.3ms/iter on 83M PRPDC) and be responsive via remote desktop; 5GB ram occupied, 11 available. I had a Radeon VII on it for a while.

OK, so let's do a virtual shopping basket on eBay - LOL, while searching just now, eBay decided that my preferred language was Russian, "based on your user profile we have decide that you are a Putin stooge" - see attachment:

MoBo: $75, new

CPU: $180, used -- that seems pricy based on my needing the build mainly to host multi-GPUs. Ken, are there any lesser CPUs this mobo can host?

Memory: Haven't been following memory pricing recently, but could either order some cheap used ddr3 or perhaps pull one of two 4GB sticks I have in my Haswell, since 4GB is more than enough for that's system's needs.

[paulunderwood]

https://www.asrock.com/mb/Intel/H81%20Pro%20BTC/ says this board supports "Supports New 4th and 4th Generation Intel® Xeon® / Core™ i7 / i5 / i3 / Pentium® / Celeron® Processors (Socket 1150)"

It would run okay with a Celeron Certainly with a low-end i5 like a 4570(k)

[ewmayer]

Originally Posted by paulunderwood

https://www.asrock.com/mb/Intel/H81%20Pro%20BTC/ says this board supports "Supports New 4th and 4th Generation Intel® Xeon® / Core™ i7 / i5 / i3 / Pentium® / Celeron® Processors (Socket 1150)"

It would run okay with a Celeron Certainly with a low-end i5 like a 4570(k)

So, something like this cheap used cpu/mobo/ram bundle?

Looking at the PCI slots for this board, multi-Radeon-VII would have one in the single PCIe 2.0 x16 slot and each of the remaining ones using a PCIe 2.0 x1 slot with x16 extender?

And what kind of gpuOwl performance hit should one expect from running in a PCIe 2.0 slot instead of a 3.0?

[kriesel]

Originally Posted by ewmayer

So, something like this cheap used cpu/mobo/ram bundle?

Looking at the PCI slots for this board, multi-Radeon-VII would have one in the single PCIe 2.0 x16 slot and each of the remaining ones using a PCIe 2.0 x1 slot with x16 extender?

And what kind of gpuOwl performance hit should one expect from running in a PCIe 2.0 slot instead of a 3.0?

If I recall correctly, per Mihai, PCIe 3 vs 2 and x16 vs x1 impact is minor. The cooling advantage may be more significant than the occasional data transfer rate.

On my system, I went with the higher cost i7-4790K because I intended to work the cpu hard with a base load of prime95. And initially with a single 8Gb DIMM, and got ~15 ms/iter prime95 for 4.5M fft; now with two DIMMs, it's ~8.3ms/iter, quite a speedup for the little I spent on the last DIMM. And it will let me do some P-1 on occasion. Your gpus with 16GB on each Radeon VII will handle that too.

Ernst, do you plan to remove the bracket from one of your gpus to mechanically allow use of the x16 slot?