Building a 4K-ready loungeroom PC on a budget means getting right back to the basic question: how much 4K gaming are you expecting? Your answer determines whether ‘budget’ and ‘4K’ can co-exist in the same sentence.
Provided you can stand the noise of the old PSU fan, you could be tempted to press-gang your old left-over PC into service – and there’s even a chance it’ll work.
Video playback of 4K content at 30fps might just work on as little as a late-model Core i3 box – even on integrated GPUs, provided you use a video codec with iGPU-hardware accelerated support.
However, the more pressing problem will be a lack of 4K video transmission support – the old HDMI v1.4 standard on most PCs and notebooks will support 4K but only to a 30Hz refresh rate.
That may be enough for movie playback on a 4K TV, but no 4K monitor will look worth its money with less than a 60Hz signal and to get that, you’ll need an HDMI 2.0 port or DisplayPort 1.2 connection, along with multi- (MST) or single-stream transport (SST) GPU drivers to suit your gear.
But GPU maker Nvidia quietly released a band-aid solution in June 2014 for those using older ‘Kepler’ GK-class GPUs (generally those down to and including the GeForce GTX 650).
Beta R340 drivers enabled these GPUs to pump out 4K video at 60Hz refresh rate over HDMI v1.4 using the ‘chroma subsampling’ technique we mentioned previously to drop the colour space down to 4:2:0 YCbCr. The pixel resolution remains the same, but the colour accuracy drops, along with the overall signal bandwidth, back to within HDMI v1.4 territory.
If you already have at least a GeForce GTX 650 GPU, you just need the latest driver (352.86 WHQL at time of writing).
Now, we can’t guarantee every 4K TV will recognise this signal, since it’s a workaround and outside normal spec. Your TV must support YCbCr 4:2:0 over HDMI, it reportedly doesn’t work with multi-card SLI and even if it does work, the colour compression won’t look as good as genuine 4:4:4 YCbCr 4K video.
But if you already have all of the components, it’ll only cost you the download of a new WHQL Nvidia GPU driver to try out.
Budget build from scratch
If you’re building from scratch, however, the cheapest option for now is likely to be Intel’s NUC (Next Unit of Computing) barebones mini PCs, provided you choose one of the latest fifth-generation ‘Broadwell’ models.
Only Broadwell NUCs support 4K video at 60Hz refresh-rate – and even then, only via DisplayPort. The HDMI port is still only version 1.4 and limited to 30Hz refresh rate. Choose anything older than Broadwell and you’ll be stuck at 30Hz, regardless.
At the moment, there are three Broadwell options available – all dual-core, based on Core i3/i5/i7 U-class CPUs, starting from $399. All should be fast enough for 4K/30fps video playback, again provided you stick to H.264 and other video codecs that have iGPU acceleration support.
As we mentioned earlier, Intel’s latest GPU drivers for Haswell and Broadwell chips now include ‘hybrid’ acceleration of HEVC (H.265) and Google VP9 – but it’s apparently only adequate for 30fps content, with reports suggesting 60fps content is a struggle.
Further, all other codecs will need to be software-decoded by the CPU and with only dual-core performance, the result will likely be dropped frames at 4K resolution. If ‘video playback’ becomes ‘gaming’, keep your expectations for 4K very modest.
Gigabyte’s BRIX series NUCs are similar alternatives – the $529 fifth-gen GB-BXi5H-5200 with its 2.2GHz dual-core Core i5-5200U has Intel’s HD Graphics 5500 GPU capable of 4K@60Hz over its mini DisplayPort output.
The BXi3H-5010 features the 2.1GHz dual-core Core i3-5010U, still with HD Graphics 5500 iGPU and 4K@60Hz display output over mini-DP. This bare-bones box sells for just over $400.
Be aware, however, that we can’t guarantee any DisplayPort to HDMI 2.0 conversion will work if you’re trying any NUC-based setup with an HDMI 2.0 4K TV.
The reality is budget 4K gaming doesn’t really exist yet. We’ve already seen that a GTX 980 is working hard to hit 50fps on most FPS games at 4K resolution. A GeForce GTX 970 card will still set you back $500, yet only offer modest 4K speed.
That said, if you have a GTX 980 gaming rig already, it might be possible to force that GPU to run at a higher resolution than its connected monitor via the driver settings and stream via Steam In-Home Streaming to your budget loungeroom box and 4K TV.
There’s little information on this technique and there’s no guarantee it’ll work – but it’s something to try if you’re feeling adventurous (search ‘downsampling’).
However, given this essentially leaves us with 4K video playback and general PC work only, here’s how we’d modify our Obsidian 250D build and save around $700:
We’re not convinced Haswell Core i3 is a great idea here – wait for Broadwell, even Skylake.
2. Drop the GTX 980 card for EVGA’s GTX 960 Superclocked ACX 2.0 – The GTX 960 doesn’t have the horsepower to game at 4K, but has full hardware accelerated decoding of H.265 (HEVC) video, along with H.264, VC-1 and MPEG-2 via PureVideo.
It supports HDMI 2.0 and DisplayPort 1.2 connectivity to deliver 4K @ 60Hz. The good news? At only $280, you save $550 on the GTX 980 cost.
4. Swap 240GB Sandisk Ultra II SSD for 120GB version – stream your content and you won’t need a large-capacity SSD. Save $50.
Ultimately, a 4K loungeroom PC done properly still needs relatively deep pockets, but you might be able to rig up something to get you out of trouble while the technology matures.
Beware your HDMI cables
If you get screen flashes or lock-ups, it could well be the cabling – don’t assume your $3 HDMI cable from eBay will be up to the job.