brob

At the moment DDR5 has issues with higher speed memory in 4 slots. If you are thinking of adding more memory later you might consider starting with a 2x32GB or 2x48GB DDR5-6000 CL32 kit.

This is why I suspect the external drive. The chance of having two bad new drives from different companies and different tech is HIGHLY unlikely. Two drives from the same mfg and batch? Sure, I can see that. But two companies, one m.2 and one SATA? Nope. It's not the drives. Its something else.

That's a respectable computer for those and other tasks, but it will suck quite a bit during the gap where you have no GPU.

PCPartPicker Part List
 
CPU: AMD Ryzen 5 7600X 4.7 GHz 6-Core Processor (£199.50 @ Amazon UK) 
CPU Cooler: Thermalright Phantom Spirit 120 SE 66.17 CFM CPU Cooler (£35.00 @ Computer Orbit) 
Motherboard: MSI PRO B650M-A WIFI Micro ATX AM5 Motherboard (£159.97 @ Amazon UK) 
Memory: ADATA XPG Lancer Blade 32 GB (2 x 16 GB) DDR5-6000 CL30 Memory (£109.00 @ Computer Orbit) 
Storage: Western Digital Black SN770 1 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive (£66.54 @ Amazon UK) 
Video Card: Inno3D Twin X2 GeForce RTX 4060 8 GB Video Card (£271.99 @ MoreCoCo) 
Case: Deepcool CC360 ARGB MicroATX Mini Tower Case (£49.00 @ Computer Orbit) 
Power Supply: Corsair RM850e (2023) 850 W 80+ Gold Certified Fully Modular ATX Power Supply (£99.95 @ Amazon UK) 
Total: £990.95
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2024-04-21 18:34 BST+0100

PCPartPicker Part List
 
CPU: AMD Ryzen 5 7600X 4.7 GHz 6-Core Processor (£199.50 @ Amazon UK) 
CPU Cooler: Thermalright Phantom Spirit 120 SE 66.17 CFM CPU Cooler (£35.00 @ Computer Orbit) 
Motherboard: MSI PRO B650M-A WIFI Micro ATX AM5 Motherboard (£159.97 @ Amazon UK) 
Memory: ADATA XPG Lancer Blade 32 GB (2 x 16 GB) DDR5-6000 CL30 Memory (£109.00 @ Computer Orbit) 
Storage: Western Digital Black SN770 1 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive (£66.54 @ Amazon UK) 
Video Card: Inno3D Twin X2 GeForce RTX 4060 8 GB Video Card (£271.99 @ MoreCoCo) 
Case: Deepcool CC360 ARGB MicroATX Mini Tower Case (£49.00 @ Computer Orbit) 
Power Supply: Corsair RM850e (2023) 850 W 80+ Gold Certified Fully Modular ATX Power Supply (£99.95 @ Amazon UK) 
Total: £990.95
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2024-04-21 18:34 BST+0100

If you like LianLi cases the 216 is bigger and can hold a 360mm rad and the biggest GPU
 

This combination should be able to fit without a problem.

Some Focus SFX are Tier B. Focus ATX and other SFX models are Tier A. https://cultists.network/140/psu-tier-list/
 

You can use es.pcpartpicker.com for availability and pricing in Spain.
 
I'd suggest using the more powerful i7-14700K. It has 4 more efficiency cores than the i7-13700K.
 
PCPartPicker Part List
CPU: Intel Core i7-14700K 3.4 GHz 20-Core Processor  (€434.89 @ LIFE Informatica) 
CPU Cooler: Thermalright Phantom Spirit EVO 69 CFM CPU Cooler  (€65.90 @ Amazon Espana) 
Motherboard: MSI MAG Z790 TOMAHAWK WIFI ATX LGA1700 Motherboard  (€243.73 @ LIFE Informatica) 
Memory: Corsair Vengeance 64 GB (2 x 32 GB) DDR5-6000 CL30 Memory  (€254.99 @ Corsair) 
Storage: Western Digital Black SN770 2 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive  (€118.39 @ Amazon Espana) 
Video Card: MSI GAMING X SLIM GeForce RTX 4080 SUPER 16 GB Video Card  (€1160.00 @ PC Componentes) 
Case: Lian Li LANCOOL 216 ATX Mid Tower Case  (€108.17 @ Coolmod) 
Power Supply: Deepcool PX1000G 1000 W 80+ Gold Certified Fully Modular ATX Power Supply  (€139.72 @ Amazon Espana) 
Total: €2525.79
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2024-04-17 18:48 CEST+0200

You can use es.pcpartpicker.com for availability and pricing in Spain.
 
I'd suggest using the more powerful i7-14700K. It has 4 more efficiency cores than the i7-13700K.
 
PCPartPicker Part List
CPU: Intel Core i7-14700K 3.4 GHz 20-Core Processor  (€434.89 @ LIFE Informatica) 
CPU Cooler: Thermalright Phantom Spirit EVO 69 CFM CPU Cooler  (€65.90 @ Amazon Espana) 
Motherboard: MSI MAG Z790 TOMAHAWK WIFI ATX LGA1700 Motherboard  (€243.73 @ LIFE Informatica) 
Memory: Corsair Vengeance 64 GB (2 x 32 GB) DDR5-6000 CL30 Memory  (€254.99 @ Corsair) 
Storage: Western Digital Black SN770 2 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive  (€118.39 @ Amazon Espana) 
Video Card: MSI GAMING X SLIM GeForce RTX 4080 SUPER 16 GB Video Card  (€1160.00 @ PC Componentes) 
Case: Lian Li LANCOOL 216 ATX Mid Tower Case  (€108.17 @ Coolmod) 
Power Supply: Deepcool PX1000G 1000 W 80+ Gold Certified Fully Modular ATX Power Supply  (€139.72 @ Amazon Espana) 
Total: €2525.79
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2024-04-17 18:48 CEST+0200

You may want to adjust 5 to "support for multiple Nvidia GPU".
 
In 3, is HDD storage in the system really necessary or can access to network storage be used?
 
 

PCPartPicker Part List
CPU: AMD Ryzen 7 7800X3D 4.2 GHz 8-Core Processor  ($384.00 @ Newegg) 
CPU Cooler: Thermalright Peerless Assassin 120 SE 66.17 CFM CPU Cooler  ($33.90 @ Amazon) 
Motherboard: MSI MAG B650 TOMAHAWK WIFI ATX AM5 Motherboard  ($199.00 @ MSI) 
Memory: TEAMGROUP T-Create Expert 32 GB (2 x 16 GB) DDR5-6000 CL30 Memory  ($102.99 @ Amazon) 
Storage: Western Digital Black SN850X 2 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive  ($154.99 @ Walmart) 
Video Card: Sapphire PULSE Radeon RX 7700 XT 12 GB Video Card  ($399.99 @ Newegg) 
Case: Lian Li LANCOOL 216 ATX Mid Tower Case  ($99.99 @ Amazon) 
Power Supply: ADATA XPG Core Reactor II 850 W 80+ Gold Certified Fully Modular ATX Power Supply  ($99.99 @ Amazon) 
Total: $1474.85
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2024-04-16 10:41 EDT-0400

The AMD 7800X3D strikes me as a more suitable CPU for this use case.
 
PCPartPicker Part List
 
CPU: AMD Ryzen 7 7800X3D 4.2 GHz 8-Core Processor ($388.09 @ Amazon) 
CPU Cooler: Thermalright Peerless Assassin 66.17 CFM CPU Cooler ($32.90 @ Amazon) 
Motherboard: MSI MAG B650 TOMAHAWK WIFI ATX AM5 Motherboard ($199.00 @ MSI) 
Memory: TEAMGROUP T-Create Expert 32 GB (2 x 16 GB) DDR5-6000 CL30 Memory ($102.99 @ Amazon) 
Storage: Western Digital Black SN850X 2 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive ($154.99 @ Walmart) 
Video Card: Asus DUAL OC GeForce RTX 4070 SUPER 12 GB Video Card ($599.99 @ Amazon) 
Case: Fractal Design Pop Air ATX Mid Tower Case ($79.97 @ Amazon) 
Power Supply: SeaSonic FOCUS GX-850 ATX 3.0 850 W 80+ Gold Certified Fully Modular ATX Power Supply ($109.99 @ Amazon) 
Optical Drive: LG WH14NS40 Blu-Ray/DVD/CD Writer ($54.99 @ Amazon) 
Monitor: Dell G2724D 27.0" 2560 x 1440 165 Hz Monitor ($199.99 @ Dell Technologies) 
Total: $1922.90
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2024-04-15 15:09 EDT-0400

The 5200 figure isn't the whole picture, and the 128GB figure is out of date. 
 
The 7900 officially supports a maximum of 5200MT/s, but it also supports memory overclocking and in practice every Ryzen 7000 series chip should be able to do at least 6000MT/s. As for the 128GB figure, the 7900 was released before 48GB DIMMs were a thing, so it would have been weird for them to say that it supports 192GB of RAM when there was no physical way to install that. It will recognize and run with 192GB of RAM installed, though odds are you'll be limited to speeds below 4400MT/s due to 4 high capacity DIMMs being very difficult for the memory controller to drive. It should also support 256GB of RAM once the 64GB unbuffered DIMMs release to the general public later this year, though again with similar speed restrictions. 
 
 
One thing I'd like to mention though is that if you are looking at the 2x48GB kits, try to avoid the ones rated for 5600 CL40, 6000 CL40, and all the other high CAS latency kits. Those kits are usually Micron based, and those can have weird stability and compatibility issues depending on the motherboard and BIOS revision. The SK Hynix based kits (the ones with a low CAS latency) are not that much more up front and are better for overall stability and performance as well. 
https://pcpartpicker.com/product/jn26Mp/gskill-ripjaws-s5-96-gb-2-x-48-gb-ddr5-6400-cl32-memory-f5-6400j3239f48gx2-rs5k
That is currently the cheapest SK Hynix based kit in the US, though just keep in mind that you will not be able to just enable XMP due to 6400 being a bit too fast for most CPUs, so you'll want to lower the speed to 6000MT/s just in case. 

Looks good. You might consider a memory kit that includes EXPO profiles instead of just XMP ones. https://fi.pcpartpicker.com/product/Gk88TW/adata-xpg-lancer-blade-32-gb-2-x-16-gb-ddr5-6000-cl30-memory-ax5u6000c3016g-dtlabbk
 

It needs a PSU. Ideally an 850W ATX 3.0 compliant model with native support for the 12VHPWR connector used by the GPU.
 
If one is going to use an AIO for CPU cooling I'd suggest at least a 280 but preferably a 360.
 
Not knowing any of the information asked for in 
It's pretty difficult to comment further.

Pcpartpicker uses manufacturer specs. AMD still lists the CPU with max memory of 128GB.
 

I suspect the AIO will have issues with the top mounted 140mm fan closest to the front. You may want to use 120mm fans in the top.

Pcpartpicker uses manufacturer specs. AMD still lists the CPU with max memory of 128GB.
 

One could use an i9-14900(K) instead, but it only adds four e-cores and some added performance.
 
PCPartPicker Part List
 
CPU: Intel Core i7-14700K 3.4 GHz 20-Core Processor (€439.88 @ Amazon Belgium) 
CPU Cooler: ARCTIC Liquid Freezer II 360 Rev. 2 56.33 CFM Liquid CPU Cooler (€108.85 @ Megekko) 
Motherboard: MSI MAG Z790 TOMAHAWK MAX WIFI ATX LGA1700 Motherboard (€299.00 @ Megekko) 
Memory: Corsair Vengeance 96 GB (2 x 48 GB) DDR5-6000 CL30 Memory (€396.86 @ Azerty) 
Storage: Samsung 990 Pro 2 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive (€173.16 @ Azerty) 
Storage: Samsung 990 Pro 4 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive (€312.95 @ Megekko) 
Video Card: MSI VENTUS 2X BLACK OC GeForce RTX 4060 8 GB Video Card (€308.99 @ Azerty) 
Case: Lian Li LANCOOL 216 ATX Mid Tower Case (€95.16 @ Azerty) 
Power Supply: SeaSonic FOCUS GX-750 ATX 3.0 750 W 80+ Gold Certified Fully Modular ATX Power Supply (€118.16 @ Azerty) 
Total: €2253.01
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2024-04-11 23:18 CEST+0200

Both AMD and Intel are expected to release new CPU generations around the same time RTX 5000 GPU make an appearance. 
 
Intel Arrow Lake is expected to use a new 2nm process. A shrink of that magnitude suggests significant changes in features, power and cooling requirements. Certainly it is expected to use a new socket which means all new motherboards.
 
AMD Zen 5 is also expected by year-end. Rumor is there will be new chipsets as well. So even looking at current motherboards is not that productive.
 

Added more details to use cases (gaming and data science).

Oh i see!!! what makes me wonder then why they only test 2 slots with a 4 stick kit... wtf haha 
But totally make sense what you say! Thanks for pointing that out 🙂

Yes the CPU is totally fine, I know friends using it too and they hadn't have a single problem with it. 
I do mostly Texturing in Mari that's why the 4090 and 128gb ram, and render my scenes in Houdini and Renderman. that's why the CPU and Ram. 
I haven't heard of any issue with AMD on the high-end tools, maybe Blender or Cinema4D have some issues I don't know. 

Not a good idea with DDR5. Optimal performance requires just 2 sticks.
 
 
It would be nice to know which model PSU. Asus has a couple ROG PSU lines.
 
Consider a new, white PSU that is ATX 3.0 compliant and provides native support for the 12VHPWR connector used by the GPU.
 
 
The product page has a diagram. Bottom & side intake, rear exhaust.
 
 
Consider an Intel CPU. It offers more concurrent threads and better Photoshop performance.
 
Consider a less expensive motherboard.
 
PCPartPicker Part List
CPU: Intel Core i7-14700K 3.4 GHz 20-Core Processor  (£384.47 @ Amazon UK) 
CPU Cooler: Lian Li Galahad II LCD 79.9 CFM Liquid CPU Cooler  (£229.00 @ Computer Orbit) 
Motherboard: MSI PRO Z790-A MAX WIFI ATX LGA1700 Motherboard  (£249.98 @ Amazon UK) 
Memory: G.Skill Trident Z5 RGB 32 GB (2 x 16 GB) DDR5-6000 CL30 Memory  (£152.71 @ Newegg UK) 
Storage: Samsung 990 Pro 2 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive  (£159.99 @ Amazon UK) 
Video Card: Asus TUF GAMING OC GeForce RTX 4070 Ti 12 GB Video Card  (£749.00 @ Computer Orbit) 
Case: Lian Li O11 Vision ATX Mid Tower Case  (£129.99 @ AWD-IT) 
Power Supply: Deepcool PX850G WH 850 W 80+ Gold Certified Fully Modular ATX Power Supply  (£179.93 @ Newegg UK) 
Case Fan: Lian Li UNI FAN TL LCD 120 90.1 CFM 120 mm Fans 3-Pack  (£135.00 @ Computer Orbit) 
Case Fan: Lian Li UNI FAN TL LCD 120 Reverse Blade 83.4 CFM 120 mm Fans 3-Pack  (£135.00 @ Computer Orbit) 
Total: £2505.07
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2024-04-10 00:43 BST+0100
 

GF3 1200W and below are highly rated Tier A.