Got my Z590 dark today and could not resist the temptation to at least power it up and throw Win10 on it for some quick testing.
 
Installed a Sabrent Rocket NVMe 4.0 in the middle slot:
 

 
CPU:
 

 
Spread some "KingPin" KPx paste that came with my Optimus Foundation block on it:

 
Block installed.  I don't like that there is no metal backplate on the back where the fasteners go.  If you get carried away with the thumb screws, I think you could easily crack the mobo.
 

 
Pretty it ain't, but it did post just fine and I was able to pick XMP1 and gear 1 with my 3600 C14 ram:
 

 
Looks like I didn't do a great job flushing the old 480 rad I had laying around:
 

 
Pretty sure it won't impact performance/cooling any, but I'll probably take it apart to clear the crud out, but I might wait until I have it mounted in my chassis with the 2nd 480 since it will probably shed some as well.
 
I plan to OC the CPU before adding my pair of 3090 FTW3 Ultra's for some Port Royal runs.

Nice! Happy to see some pics of a Dark in the wild.

wait is the middle slot 4.0?

Nope. M2 & M3 are Gen 3.
Only M1 is Gen 4.
 
see page 19 of manual:
 
13. M.2 Socket 3 Key-M 110mm (PM1)
M.2 is an SSD form factor standard, which uses up to four PCIe lanes and
utilizes up to Gen4 speeds, depending upon the device used. Most popularly
paired with NVMe SSDs, this standard offers substantially faster transfer speeds
and seek time than SATA interface standards. All M.2 devices are designed to
connect via a card-bus style connector, secured by bolting into place, and
powered by the connector – rather than a dedicated data cable and power cable.
This slot support device lengths of 110mm, 80mm, 60mm, and 42mm.

14. M.2 Socket 3 Key-M 110mm (PM2)(PM3)
M.2 is an SSD form factor standard, which uses up to four PCIe lanes and
utilizes up to Gen3 speeds. Most popularly paired with NVMe SSDs, this
standard offers substantially faster transfer speeds and seek time than SATA
interface standards. All M.2 devices are designed to connect via a card-bus style
connector, secured by bolting into place, and powered by the connector – rather
than a dedicated data cable and power cable.
These slots support device lengths of 110mm, 80mm, 60mm, and 42mm.
 
and on page 20:
 
The 20 RKL Gen4 PCIe lanes are pulled from the CPU and shared with the x16
PCIe slot 2 (PE2) and M.2 Key-M 110mm (PM1)
 

Didn't realize they were not all 4.0 slots.  Just moved it to slot 1.  I noticed it only says Gen 4 on the silkscreen for slot 1.  Should have paid better attention I guess.  I figured I would get better heat distribution using the middle slot, but it would have probably need negligible anyway.

The Z590 Dark actually tells you which M.2 slot is PCIe 4.0 directly on the board - no manual needed. lol
 

 
...and I don't even own the board.
 
Nice photographs tech brother! Your tower of cooling power is SWEET! 

Lol, yeah I just updated my post above yours as I noticed that when I moved it to slot 1.  It was late last night when I got a chance to play with it, ok?  Oh, and I might have had an Old Fashion or two.  :)
 
I got an EVGA XR1 capture device, so I might play with as I start messing with OC settings to see if I can capture some nice images instead of the usual camera shots of the screen.

WebsterRKL
The Z590 Dark actually tells you which M.2 slot is PCIe 4.0 directly on the board - no manual needed. lol
 

 
...and I don't even own the board.
 
Nice photographs tech brother! Your tower of cooling power is SWEET! 

Now that's embarrassing.
Shows you how observant I am.
It's right there is his picture.

frankd3

WebsterRKL
The Z590 Dark actually tells you which M.2 slot is PCIe 4.0 directly on the board - no manual needed. lol
 

 
...and I don't even own the board.
 
Nice photographs tech brother! Your tower of cooling power is SWEET! 

Now that's embarrassing.
Shows you how observant I am.
It's right there is his picture.

lol. When you're working with a brand new and beautiful Z590 Dark board, the 1st few days - no one is expected to have a clear head. 
 
Trying to post a screenshot of CrystalDiskMark benchmark results pclausen can expect for PCIe 4.0 M.2 SSD Reads and Writes, but the thread window just stalls mid upload, ho hum.
 
That way you can make certain your PCIe 4.0 slot is operating at full speed.
 
I'll keep trying

Here's my result from CrystalDiskMark:
 

 
Those numbers are ok, but then I ran the same test on my 570X rig (5950X) which edges it out on sequential reads and puts the smack down on random read/write compared to the Z590:
 

 
The 570X rig has dual Sabrent 1G NVMe 4.0 drives in it and I did the test to the D: game drive and not the OS drive, but I was not expecting that big of a difference, especially since the Z590 has a clean Win 11 install (both are on Win11).  To be fair, the X570 is running a 17% or so OC where the Z590 is stock except for memory being set to XMP1 gear 1.
 
Full specs on each rig:
 
Intel Rig:
Mobo: EVGA Z590 Dark
CPU: 11900K
RAM: G.Skill Trident Z Neo F4-3600C14D-16GTZNB (single rank)
M.2: 1x Sabrent Rocket NVMe 4.0
GPU: PNY GT720 (will be replaced with 2x EVGA 3090 FTW3 in SLI once CPU is tuned)
CPU Cooler: Optimus Foundation
Pump: EKWB EK-Quantum Kinetic TBE 300 D5 PWM Pump-Reservoir
Rad: 1x XSPC 480 (will be 2x EXPC 480 once the 3090's are on water)
PSU: EVGA 1200 P2
 
AMD Rig:
Mobo: Asus ROG Crosshair VIII Formula
CPU: 5950X
RAM: G,Skill Trident Z Neo F4-3600C16D-16GTZNC
M.2: 2x Sabrent Rocket NVMe 4.0
GPU: EVGA RTX 3090 KingPin HC
CPU Cooler: XSPC
Pump: EKWB EK-XRES 140 Revo D5 PWM Pump-Reservoir
Rad: 480 Thick (forget brand/model)
PSU: Corsair AX1500i
 
Will be interesting to pit the 2 rigs against each other once the Intel rig has been tweaked.