evga ftw3 - 105MHs/stock speeds/ fans 90% manually set, to keep it cool no problems
msi ventus - 107MHs/stock speeds/ fans 90% manually set, to keep it cool, no problems

3090 is not best for mining in terms of a output bang, to my opinion. 3080 or 3080 would be, due to the fact that price is half and performance i slightly less, so best bang for a buck.

i have seen this problem, dude was was using nicehash though. We tried various ways to pinpoint the problem and came to conclusion its claymnoore problem, had to permanently disable it. After it was done, phoenix mier took over and was working fine since. Since everything was fine after we did not bother to create ticket with this problem.

tested MSI 6900XT today - does 58-61MHs at stock clocks @ 230watt (gpu) on various miners. costed 1100$
evga ftw3 3090 does 107MHs @ 300-320watt (gpu) costs 2100$

I tested it with 4000Mhz ram (oc) - no significant difference vs 3200Mhz(OC)

3950X does a bit better vs 3900 16700hs approx - same with ram, not much difference between 3200/4000
I will try to post screenshot later

I needed to build two more AMD desktops for my clients and went to a local store to pickup components...craziness!
They used to have 3900x with coolers (retail packaging) for 400$ just a couple days ago, now they are 550$+tax(thats all they had), absolutely no 5xxx series, not even low end...no video cards AT ALL, some SSD's are also emptied... daam!

Tried it on various boards, including same setup as 3900x. Observations:
5900x - consumes less power (10-15W), Runs cooler (about 8-11'C) gives same or just a bit higher hash rate in my case biggest difference was 350H/s Funny thing is - it does better on cheaper boards, lol. Conclusion - not worth upgrade.

Got my hands on 5900x, will build and try it in the next few days

In terms for motherboard - i would go with MSI brand, they have very neat, 2 buttons that do light over clock for you. All you do is press button (its in bios) and reboot, check stability and if it works you are all good. No need to know all backend tricks with clocks, voltages or timings. For example <200$ x570 MPG GAMING PLUS is not expensive and performs good. The good memory is a must. You can even use standard 2133 or 2400 (SPD) "green" sticks and you will get 13khs on 3900x. I tried it with stock wraith cooler and i think its a bit small for everclocking as cpu gets to 80'c range...you can get COOLER MASTER like this https://www.newegg.com/cooler-master-hyper-212-evo-rr-212e-20pk-r2/p/N82E16835103099 its 35$ and works better then original wraith cooler. Just add rpm's or second fan and you are good to go. But anything like NOCTUA or equal or watercooler with 3 fans (360mm) will be the best.

i have 3090 ftw3 and it does 107Mhs

sadly the scalpers lined up like 24 hours ahead of release and camped all night... i came in the morning right by opening and there was NOTHING on the shelves... no amd cpus nor any 3000 nvidias or 5000 or 6000 series amd gpus...

have anyone seen real hashing of 3950? On the internet values are sooo different, starting from 13khs up to 20khs...like whats the stock clock hashrate with good board/mem timings, but WITHOUT OVERCLOCK...

when do they have new threadrippers coming out ?

Well i am hoping the programmers can utilize unicache on zen3 somehow...but if not then 3900x or 3950x are fine with me.

By the way the AMD ROADMAP shows AMD ZEN4 for 2021 and ZEN5 for 2022... New socket comes out in 2H 2021 afair.

At this point DEC 1 is the DATE.
initially it was jan 1 2021, but apparently they made it sooner. Be ready to deposit your ETH for %, keep in mind that IT IS 1 WAY ROAD as of right now. Can reverse that.

without mining software updates. WITH CURRENT MINER VERSIONS.

which is a bit saddening. However i expect about 15khs after miners updates.

64->7mb cache plus 16+16+16+16mb cache in 3000 series vs 72 unicache for all cores. Stock freqs are same except TURBO mode, when 5000 series is a bit faster.

we shall see.

In local store all 5950 and 5900 series were sold out instantly, the 5800, and below are not and plentiful available.

5900 reported to have SAME HASHRATE as 3900x ~13500khs

So added more ram, now its quad channel. no change in hash rate.
looks like this is it:
https://www.win-raid.com/t3874f16-GUIDE-Haswell-E-EP-Xeon-CPUID-F-Turbo-Unlock.html
http://www.miyconst.com/Blog/View/2081/xeon-e5-2600-v3-turbo-boost-unlock
http://www.xtremesystems.org/forums/showthread.php?293290-Various-Overclocker-discovers-Xeon-E5-V3-Errata-Engineers-exploit-to-unlock-Turbo

- never heard of this, can you point me?

I got my e5 2070 v3 installed. temps are good. I Get 5800hs out of both. Mem runs on two channels, bought more sticks, will get them next week installed, curious if 4 channels will do any good...
Comparing to two E5 2665 V2, the v3's are less powerful. I get 6200-6300Hs out of V2s

- this is a bit too much of $ in...

- this is very reasonable, where did you get numbers from?

i have found locally 2670 v3, will install soon and see what they are capable of

so for example E5 2670 V3 ( 12core 30mb 2,3ghz) vs E7 8893 (4core 45mb 3,2ghz)  
2670 should be better right?