lmaobadatmath

My thumb rule for prebuilts is to always look for deals https://www.microcenter.com/product/507383/xps-8930-desktop-pc This one, for instance is a great deal.

That 9400 would bottleneck the 2080, I would probably get a 2070 and a 9600k instead and make use of that z390 board at the same time.

That PSU is pretty junk, it might not be providing adequate power to the GPU. "Critical Process Died" usually indicates hardware failure. The Rx 590 is a fairly power hungry card, that could be the issue

Get something like this PCPartPicker Part List Type Item Price CPU AMD - Ryzen 7 2700X 3.7 GHz 8-Core Processor $292.89 @ OutletPC Motherboard Gigabyte - B450 I AORUS PRO WIFI Mini ITX AM4 Motherboard $119.99 @ Amazon Memory Corsair - Vengeance LPX 32 GB (2 x 16 GB) DDR4-3000 Memory $169.99 @ Corsair Storage Western Digital - Blue 1 TB M.2-2280 Solid State Drive $109.89 @ OutletPC Video Card Asus - Radeon RX 580 8 GB AREZ Dual OC Video Card $169.99 @ Newegg Business Case Fractal Design - Define Nano S Mini ITX Desktop Case $75.98 @ Newegg Power Supply Corsair - TXM Gold 550 W 80+ Gold Certified Semi-Modular ATX Power Supply $57.98 @ Newegg Prices include shipping, taxes, rebates, and discounts Total (before mail-in rebates) $1046.71 Mail-in rebates -$50.00 Total $996.71 Generated by PCPartPicker 2019-04-30 13:50 EDT-0400

I totally understand that, my basement has at least 10 monitors laying around connected to different servers and systems.

eyefinity

You mean 2x optical zoom

It won't be a BIOS issue since the problem only occurs when he uses two RAM sticks

Glad he got the money back. If any of the pins are bent then that might be causing that.

Fedora, is by far my favorite. But I have started liking Manjaro as well.

Sounds like a dead memory controller, can you check the CPU for any bent pins and/or see if you can get a refund from it's previous owner or at least get some money back?

If you, OP ,can budge 30 pounds over budget, get this PCPartPicker part list / Price breakdown by merchant Type Item Price CPU AMD - Ryzen 5 1600 3.2 GHz 6-Core Processor £116.39 @ Newegg UK Motherboard ASRock - B450M-HDV Micro ATX AM4 Motherboard £52.73 @ CCL Computers Memory Crucial - Ballistix Sport LT 8 GB (2 x 4 GB) DDR4-2666 Memory £45.70 @ Amazon UK Storage Crucial - BX500 120 GB 2.5" Solid State Drive £17.98 @ Amazon UK Video Card XFX - Radeon RX 580 8 GB GTS XXX ED Video Card £169.94 @ AWD-IT Case BitFenix - Comrade ATX Mid Tower Case £29.41 @ Aria PC Power Supply Corsair - CXM (2015) 450 W 80+ Bronze Certified Semi-Modular ATX Power Supply £48.48 @ Amazon UK Prices include shipping, taxes, rebates, and discounts Total £480.63 Generated by PCPartPicker 2019-04-25 17:14 BST+0100

This is all that I can put together for that budget PCPartPicker part list / Price breakdown by merchant Type Item Price CPU AMD - Ryzen 5 1600 3.2 GHz 6-Core Processor £116.39 @ Newegg UK Motherboard ASRock - B450M-HDV Micro ATX AM4 Motherboard £52.73 @ CCL Computers Memory Crucial - Ballistix Sport LT 8 GB (2 x 4 GB) DDR4-2666 Memory £45.70 @ Amazon UK Storage Crucial - BX500 120 GB 2.5" Solid State Drive £17.98 @ Amazon UK Video Card XFX - Radeon RX 570 8 GB Video Card £130.61 @ Amazon UK Case BitFenix - Comrade ATX Mid Tower Case £29.41 @ Aria PC Power Supply Corsair - CXM (2015) 450 W 80+ Bronze Certified Semi-Modular ATX Power Supply £48.48 @ Amazon UK Prices include shipping, taxes, rebates, and discounts Total £441.30 Generated by PCPartPicker 2019-04-25 17:12 BST+0100

For that price, get the RTX 2080 Ti instead. That is an expensive af 1080Ti. PCPartPicker part list / Price breakdown by merchant Type Item Price CPU AMD - Threadripper 2950X 3.5 GHz 16-Core OEM/Tray Processor CPU Cooler Noctua - NH-U14S TR4-SP3 82.52 CFM CPU Cooler $79.90 @ Amazon Motherboard Asus - PRIME X399-A EATX TR4 Motherboard $299.99 @ Amazon Memory Crucial - Ballistix Sport LT 16 GB (2 x 8 GB) DDR4-2666 Memory $85.99 @ Amazon Storage Intel - 660p Series 512 GB M.2-2280 Solid State Drive $61.37 @ Newegg Video Card EVGA - GeForce RTX 2080 Ti 11 GB XC GAMING Video Card $1199.99 @ B&H Case Phanteks - Enthoo Pro ATX Full Tower Case $99.99 @ Amazon Power Supply Corsair - HX Platinum 750 W 80+ Platinum Certified Fully-Modular ATX Power Supply $103.88 @ OutletPC Prices include shipping, taxes, rebates, and discounts Total (before mail-in rebates) $1951.11 Mail-in rebates -$20.00 Total $1931.11 Generated by PCPartPicker 2019-04-25 12:04 EDT-0400

As BigRom stated, wait till Ryzen 3 arrives, it will definetely change things.