New desktop

I_have_spoken

IMHO AMD are only worth considering at the entry level, like the AMD FX-8300 which is comparable to Intel Core i3-6100.

NB for a new build, I'd find the extra £17 and specify an Intel Core i5 6500, the extra 500MHz on all cores is worth having under heavy loading.

prost

Instead of getting a desktop try a Lenovo T410 laptop (or T420). They sell for £80-110 on ebay secondhand. The big advantage is that is will use less energy so you'll save a lot in electricity costs.

You can get an adapter:
http://www.ebay.co.uk/itm/Double-Duel-PS2-To-USB-2-0-Cable-Adaptor-Mouse-Keyboard-Cable-Splitter-UK-STOCK-/262315878002?hash=item3d133ea672:g:6m0AAOSwHnFV6YJQ

which lets you plug in a ps/2 mouse & keyboard in one USB slot.

It has a vga port so you can plug in a monitor. It also has a display port so if the vga port fails then you can get a display-port-to-vga adapter:
http://www.ebay.co.uk/itm/DisplayPort-Male-Plug-to-HD15-15-pin-VGA-Female-Connection-Adapter-006829-/262100748446?hash=item3d066c089e:g:xzMAAOSw0e9UvCv1

This lets you put a second hard drive in the DVD slot:
http://www.ebay.co.uk/itm/Univer-SATA-2nd-HDD-SSD-caddy-adapter-for-Laptops-9-5mm-Optical-Hard-Drive-Bay-T-/321721218927?hash=item4ae814376f:g:u-IAAOSwcwhVJ89j

The T410 has an i5 520m processor with a benchmark of 2400 so this is easily fast enough for people who don't do lots of video encoding. The T420 has the faster 2520m (benchmark 3500).

Your old PC had a benchmark of 876. It's not particularly slow but without access to your PC I can't say why it's slow. Your boot times will decrease quite a lot with a faster PC.

These laptops use 30-40 watts of energy at most. A desktop with a low-energy processor might use about 80 watts.

The T410 has a maximum memory capacity of 8Gb 1333 Mhz memory (16Gb 1333 Mhz memory for the T420 although on some Web sites it wrongly lists it as 8Gb).

4Gb:
http://www.ebay.co.uk/itm/Kingston-ValueRAM-4GB-1X4GB-Memory-Module-DDR3-1333MHz-C3-10600-SO-DIMM-Laptop-/111324261803?hash=item19eb716dab:g:MogAAOSwFqJWp880

8Gb:
http://www.ebay.co.uk/itm/Kingston-ValueRAM-8GB-1X8GB-Memory-Module-DDR3-1333MHz-PC3-10600-SO-DIMM-Laptop-/111656104753?hash=item19ff38f331:g:0rAAAOSwBahVPX8t

Here's a forum for Lenovo laptop users:
https://forums.lenovo.com/t5/ThinkPad-T400-T500-and-newer-T/T420-RAM-Upgrade/m-p/874715

User reviews:
http://www.amazon.co.uk/LENOVO-THINKPAD-T410-2-4GHz-i5-520M/dp/B00CE81UE6/ref=pd_sim_147_3?ie=UTF8&dpID=51CibKXNiGL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=1JNDS9BZ5NFXJ6RYN7AP

If it doesn't come with a mains adapter here's one:
http://www.ebay.co.uk/itm/For-IBM-Lenovo-ThinkPad-e40-T410-T420-T510-T60-T400-Laptop-Charger-adapter-uk/331577818267?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36243%26meid%3D491632f9304e42b49369a9967d1535d2%26pid%3D100009%26rk%3D1%26rkt%3D10%26sd%3D262359757747

£14 9-cell battery for T410 T420 T510 T520 W510 W520 SL410:
http://www.ebay.co.uk/itm/9-Cell-Laptop-Battery-For-Lenovo-ThinkPad-T410-T420-T510-T520-W510-W520-SL410/231549766854?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36243%26meid%3Df270f25b55624c85bab791b355b5273c%26pid%3D100005%26rk%3D1%26rkt%3D6%26mehot%3Dpp%26sd%3D381549710702

How to replace the memory https://www.youtube.com/watch?v=X17SaHKMysc

I used to build desktops using only AMD processors but have switched to the Lenovo laptops to save energy.

You won't need any fancy graphics card but I think the laptops use the Intel HD 3000. It has a slightly higher 3D benchmark than an old Nvidia 9500 gt which, with 32 cuda cores, can be used for the FSX flight sim.

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If your Ethernet port fails then use a USB adapter: http://www.ebay.co.uk/itm/USB-2-0-To-RJ45-LAN-Ethernet-Network-Adapter-Dongle-for-PC-Win7-10-100Mbps/351603606279?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36243%26meid%3Dca7269528c694585ac6d19663fb88f4b%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D191756382216

Replacement £26 keyboard:
http://www.ebay.co.uk/itm/UK-layout-keyboard-Lenovo-ThinkPad-T420-T410-X220-T520-T510-very-good-condition/272135345756?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36243%26meid%3Ddc30cb01443846bf9d03cd65239f16ed%26pid%3D100009%26rk%3D6%26rkt%3D10%26sd%3D151481235599

Or try a £14 bluetooth keyboard with trackpad:
http://www.amazon.co.uk/TECHGEAR®-Bluetooth-Wireless-Keyboard-Microsoft/dp/B014LECUUS/ref=cm_cr_arp_d_product_sims?ie=UTF8

This lets you plug in a 2.5 inch SATA laptop hard drive externally into the Lenovo's eSATA port
(although it isn't as fast as true SATA):
http://www.ebay.co.uk/itm/eSATAp-Power-Over-to-eSATA-to-SATA-22-pin-Adapter-Cable-2-5-3-5-HDD-12V-5V-/231089124253?hash=item35cdfc339d:g:q6EAAOxy7nNTTrVo

If your headphone socket fails try a USB sound card.

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There are also DisplayPort-to-DVI adapters.

To enter BIOS press F1 when the laptop starts.

The good thing about these laptops is that there is a BIOS setting which lets it power on when the mains plug is connected.

How to open it up https://www.youtube.com/watch?v=3mj7KvuFsuU Make a note of which screws go where. (There's five sets of screws: one holding the memory cover, 10 at the back, 3 around the center, one in the top left corner, & 4 holding the fan. So you'll need five envelopes/containers: A, B, C, D, E.) You'll need something like a 'Rolson 22 Piece Precision Screwdriver Bit set', which you can find at Maplins for £3 but I find one in the 99p store. This kit is vital as you may strip a screw by using a driver of the wrong size.

To remove the drive
https://www.youtube.com/watch?v=oO8of1uEHiU

ThemeOne

I also had a Zoostorm which I had to return. However, the customer service around the return was excellent, and it was repaired to a higher spec than the original configuration.

It's been fine ever since.