[QUOTE=Jurzal;631094]
How about professional accelerators like AMD Instinct? Link: [url]https://www.amd.com/en/products/server-accelerators/instinct-mi250x[/url][/QUOTE]

Instinct MI250: those are extremely expensive, and not available for purchase (by an individual that is) anywhere.

I guess if you want to buy some multiple of 1000s of Instinct GPUs, you contact AMD sales directly and they tell you the price for the lot.

OTOH old-gen MI50 and MI60 may be found for reasonable prices. They are good GPUs, comparable to R7, with double the RAM (32GB), with ECC all-over (but ECC brings no benefit for PRP). But they have no cooling, so you'd need to improvise some cooling solution up.

[QUOTE=preda;631103]Instinct MI250: those are extremely expensive, and not available for purchase (by an individual that is) anywhere.

I guess if you want to buy some multiple of 1000s of Instinct GPUs, you contact AMD sales directly and they tell you the price for the lot.

OTOH old-gen MI50 and MI60 may be found for reasonable prices. They are good GPUs, comparable to R7, with double the RAM (32GB), with ECC all-over (but ECC brings no benefit for PRP). But they have no cooling, so you'd need to improvise some cooling solution up.[/QUOTE]

What about Radeon VII Pro vs Instinct MI50? With some home depot cooling :D
In screenshots, current retail place in Latvia e-comms.

R7 Pro has 6.5 TFLOPs FP64
MI50 has 6.7 TFLOPs FP64
R7 (nonpro) has 3.4 TFLOPs FP64

3D printed fan tunnel attachment

[QUOTE=Jurzal;631125]What about Radeon VII Pro vs Instinct MI50? With some home depot cooling :D
In screenshots, current retail place in Latvia e-comms.

R7 Pro has 6.5 TFLOPs FP64
MI50 has 6.7 TFLOPs FP64
R7 (nonpro) has 3.4 TFLOPs FP64[/QUOTE]
Per Preda a while back, even the Radeon VII at 3.46 TFLOPs FP64 & 1TBps HBM2 ram bandwidth is thought to be memory bandwidth limited in Gpuowl.
A reason to go to MI60 is greater total ram, for P-1 stage 2 on large exponents with Gpuowl.
MI60 requires Ubuntu or SLES (no Windows support); and either a server case that pushes air through the passively cooled GPU lengthwise, or a blower & adapter. Plus not all motherboards will work with an MI60:
“*PLEASE NOTE* This unit does NOT work with windows. It only works with Linux. This unit does not work with any Radeon drivers and only works with ROCm. For multiple cards to work in one system, this card typically needs a server motherboard. In our testing with a server motherboard, we are able to connect up to 4 of these MI60 cards at once, but not more than 4. We were able to connect additional cards that were not MI60 in addition to the 4 units. For example, we were able to have 4 units of MI60 and 4 units of RTX 3060 working simultaneously with a server motherboard. We have also had good luck with the Gigabyte Z390 UD motherboard working with 4 units. In order to get to 80MH on this card you must use teamredminer in C state.” [url]https://www.ebay.com/itm/125006475381[/url] & MI60 apparently requires PCIe v3 or 4. Radeon VII can run on PCIE V2 or 1.1 extenders.
[url]https://www.amd.com/en/support/server-accelerators/amd-instinct/amd-instinct-mi-series/instinct-mi60[/url]

[QUOTE=MarkVanCoutren;622308]Good evening gentlemen,

I got my year-end bonus, and I'm thinking of blowing part of it on a full-time GIMPS setup. I've been running PRP-WR on my gaming PC but I want to build a machine/machines that will be min-maxed for GIMPS. I've been focusing on large core count CPUs with fast RAM but I can't decide if it would be better to go all out on one machine or get two more modest machines. I'm looking to spend around $3k. Does anyone have any setups that worked well for them or any sage advice?

Thank you[/QUOTE]

For 3 grand you easily set up a 6 GPU rig and have change to run it. With 6 Radeon VII each drawing no more than 250w you'd need a couple of beefy PSUs. The rest of the system is chicken feed. In fact the GPU cards can be adjusted to draw 200w each -- so a couple of 1200w PSUs is recommended so that you don't fry things. Maybe two simple motherboards too with adequate PCI-E slots. The downside is that each GPU has 3 cooling fans. So the noise will be a problem -- you need a separate room for the rig, and adequate room cooling during the summer.