Does anybody plan to speculatively mine GPU coins after PoS, even if the 'paper profit' is a few pennies per day per card? If revenue < power cost, I obviously will turn my rigs off.

You could also trade your RVN for a basket of coins in order to diversify. But you are in an enviable position even at 3.8 cent RVN. Most miners years ago sold 99% of their coins instead of HODLing them and making millions. I personally missed out on hundreds of thousands of DOGE, DASH, ETH and LTC because I never saved up enough of the coins. From now on I'll never repeat that mistake again and I'll keep mining during the bear market.

What you're saying is specific to the U.S. / North America. I have to worry about the 208 volt / 240 volt difference for sure and the delta/wye stuff. The rest of the world usually has 415 / 240 wye power. I also prefer 240v delta because higher voltage = more wattage available, plus less current through cables, so higher efficiency.

Even miners within the same region or utility coverage area can have vastly different rates. Some of them can be on a fixed long-term contract for 3-4 cents while others pay public tariff rates of 5-6 cents. The GWh they signed to are already a sunk cost, so the marginal cost of their power is zero. Therefore, these big corp-o-mines will always continue mining even if BTC is $5k.

I have had more problems with new video cards than used ones. In total, I have purchased 150 used / 300 new GPUs over the past 6 years. The new ones had a DOA rate of 2-3% while the used were only DOA 1% of the time.

I don't think the RTX 3090 will be relevant for either games or mining for very long. That's why it's price has dropped like a stone. The RTX 3060 Ti will.

I have bought 100+ used video cards any only 1 or 2 had a problem that the seller refused to fix. I will not buy new video cards unless the premium is < 5% greater than used.

I have had no problems building mining rigs with two or even three power supplies. As long as the video cards are the exact same model and power sources are not mixed, the uptime has been close to 99%.

The EVGA 550GA is more than reliable enough with enough power for a single RTX 3080 Ti. Why not make use of that capacity?

FeeBay
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=RTX+3090&_sacat=0&LH_TitleDesc=0&_odkw=RTX+3060+Ti&_osacat=0&LH_BIN=1&_sop=15

The price of used RTX 3060 Ti's is <$400 for me now.

The 500-700w ATX unit is only good for 1-2 video cards, but the rig has 8-10 cards, so obviously more power is required. If I had a 10x RTX 3060 rig, it needs 2000w total. The ATX supply will cover 500w, so I need 1500w extra, which can be covered by two HP-DPS750RB supplies. Or I could have an 8-card rig and use a single HP-DPS1200FB supply. I like to have enough wattage to cover the full TDP of the cards.

Why not a 1600w ATX supply or even a 1200w one? Because they are double the price-per-watt of the server units. An EVGA 1600 P2 will cost $220 which is 13.8 cents/W. But a HP DPS-1200FB+breakout board+12v cables costs just $70 --> 5.8 cents/W.

How is that not a gamble too? At least with video cards, the investment can only lose half of it's value.

This is the only source of U.S. power cost which is somewhat reliable:

https://findenergy.com/

The map displays average residential rate by county, which obviously doesn't include cheaper tariffs that may be available or tiered usage plans. But it's a good starting point to find industrial power. Simply divide the residential price by 2.

The RTX 3080/3090 series prices would be hit the hardest by the new generation. They have been the cards that have held their value the worst so far, with the RTX 3090 being $3000 last year but now you can get them for only $1000.

Because it only costs $10-15 more to get a 600w ATX supply than a 400w unit. That is a price of 15-20 watts/$ which is excellent.

What's wrong with comparing hashrate/power usage between generations? Pascal only has 25% worse H/W compared to Turing on FLUX or XEQ. ETH is irrelevant because it will disappear one day.

I have had bad experiences with the B250 Mining Expert back in 2017/2018.

I like using a 500-700w ATX power supply for the MOBO + 1 or 2 video cards, then HP server power supplies for the remaining video cards. That is the cheapest combination while still having Gold/Platinum efficiency.

Temperatures were as high as 41°C for Riot Whinstone this week. Lol, I have no idea how they can keep operating even with their evaporative water wall. They probably shut down during peak heat anyway because electricity prices tend to be very expensive (>30¢/kWh)

Most of the U.S. hashrate is based in just 3 states: WA, TX, NY. However, I expect that to change. New mining farms will be built in Midwest or Southeast states with cheap power. ERCOT power in particular has become much more expensive. So now second-tier energy markets are becoming more attractive

The RTX 2060 super is definitely good at non-ETH algorithms, but I can find the P106-100 6GB cards for much cheaper at the same hashrate.

Did you use this motherboard yourself?

It looks like a good deal at US$60 including shipping, but I found one that supports 12 GPU's for $90. However, it doesn't include a CPU, which will cost $30.

So I have to choose between $60 for 8 GPUs (30 day wait) or $120 for 12 GPUs (5 day wait).

You're better off finding an existing mining farm who's going bankrupt and taking over the facility from them or buying them out. Sub 5-cent industrial power is hard to find these days after what happened to the natural gas market. Existing warehouses with 1MW of capacity installed are very hard to find for a reasonable rent.