Hardware & Technical Intent to do ED themed BBC B PC conversion

[Porina]

This idea has been kicking the back of my mind for a while. One of my first gaming memories was having a lesson in how to dock in the original Elite from either my brother or a cousin, I can't be sure. Why not make a PC out of an old BBC B body, gut it and fit a gaming capable PC inside it, then subtly bling it ED style?

This is very much in the planning stage. I have ideas, and some open questions.

First hurdle, what will fit? I do have a BBC B... but it is 160 miles away at my mum's house and I'm not planning on visiting any time soon. So I'm guessing a bit here. I believe it will be tall enough to use 1U rackmount stuff as a height guide. I have a small motherboard and CPU I intend to use: MSI H81M-P33 which is on the small side of micro-ATX, almost mini-ITX. In that is a i3-4150T so only dual core but it is low power so might be less of a problem to power and cool. It currently has the stock Intel cooler on it, but I might replace it with a different low profile cooler.

GPU wise is more of a problem. I want lower power, but still good enough performance to do something in Horizons. I'd define lower power as a card NOT requiring a PCIE power connector. Of existing GPUs, the 750Ti seems to be the best balance. I don't have one so it would have to be bought, and I'm holding out a little here to see if there might be a glut of used GPUs when the next gen come out later this year. I have got a PCIe 16x riser on order to allow me to put the GPU on its side.

Hard disk wont be a problem as the system already has either a small SSD or 2.5" HD, I'm not sure but either way will suffice.

Power is to be decided. I have something resembling a 1U PSU from an old Shuttle. It is rated 200W which should be enough but doesn't have fancy new connectors on it, so would need adapter cables. Alternatively I could get new to be safe. There are some 150W PicoPSUs but they need a big external power brick, and combined that doesn't work out cheap. A newer 1U PSU is also a consideration.

Ok, PC bits are not too complicated anyway, the interesting bit will be the mod itself. I'm not the first to attempt a PC mod: e.g. http://www.mini-itx.com/projects/bbcitxb/ I might be stretching things a bit by putting a GPU in though. I will need to work out a cooling plan as well. I need to research the keyboard mod later, as that will be something I want to keep operational in some way.

How can I ED it up some more? Orange. Could I shoehorn an orange LED backlight under the keyboard? Or just an orange under-computer glow? There is a transparent plastic strip over the keyboard to allow labelling of the F-keys, so something could be done there too.

As a final little trick, when the BBC B is powered on, there was a two tone noise. I'll also want to reproduce that in some way.

 

[MickyG1982]

Well, power wise the 750ti should be OK at ED, though it will struggle on Horizons landings. The PSU, you require should manage 400W +, the 200W one you are looking at will not be able to handle it. It might increase the realism a bit with some ED style dashboard sparks though...

What might be worth looking at is going down AMD's APU route as, certainly for core ED, they will provide decent performance without the need for a discrete card. This should keep your power requirements to a minimum.

 

[Porina]

I've decided that APUs are too weak. If I were to go that route I could instead go to Broadwell, actually, I never benched that so that's still on my to do list. If not the 750Ti, maybe a 950 is a possibility too but that's more cost. Again I'm basing this on only needing PCIe slot power, not extra connector power.

No idea where you pulled 400W from. That's massive overkill. PSU + GPU described will take just over 100W under maximum load. Where's the rest going? A decent quality 150-200W is plenty.

 

[CMDR MAIN SEQUENCE]

Does your Beeb still function? Don't think I could bring myself to gut mine knowing that it was still working (I'll get around to testing it one of these days), too many fond memories But good luck with your project.

 

[Porina]

It has been years since it was last in use, but there was a fault in that mode 7(? - default teletext mode) didn't display any more but other modes still worked. Not sure I can find the bits to get it going again in any useful way. I'm sure someone could find anything I extract useful for spares.

 

[MickyG1982]

I've decided that APUs are too weak. If I were to go that route I could instead go to Broadwell, actually, I never benched that so that's still on my to do list. If not the 750Ti, maybe a 950 is a possibility too but that's more cost. Again I'm basing this on only needing PCIe slot power, not extra connector power.

No idea where you pulled 400W from. That's massive overkill. PSU + GPU described will take just over 100W under maximum load. Where's the rest going? A decent quality 150-200W is plenty.

Ok, maybe not 400W, but Nvidia's own website recommends a 300W PSU for the 750ti or a 350W PSU for the GTX 950.

Using a lower powered supply generates more heat & reduces the efficiency not to mention putting more stress on the PSU. Having a good bit of power overhead is generally not a bad thing on any build.

 

[Porina]

For sure I'll be careful not to overload it, especially the 12V rail that everything modern uses and that rail tends not to be as strong on older PSUs. The system recommendations are just for them to be safe so people hopefully don't try to put it in under-powered systems. Also for efficiency, there is a bit of a curve to it so the optimal position is fairly but not highly loaded. Even if I went for the 150W, estimated peak 110W draw would be around 75% which is still in the comfort zone, and realistically it wouldn't get that high in gaming usage. Only if I decide I like running Prime95 and furmark at the same time might I worry...

On that note, the old 200W PSU I've just checked and it is unsuitable after all. The 12V rail is only 10A, so around 120W. I feel that's a bit too close to the limit. The rest of the power available on the 3.3V and 5V lines will largely go unused. So I will be shopping for a new PSU after all.

 

[Porina]

Just did a phase of shopping.

I went with a 160W PicoPSU with 150W brick. I thought it would be nice to have something fanless, and if there is room I hope to put the brick inside the case anyway. There is still some uncertainty here, in that the PSU only outputs a sustained 8A at 12V, for 96W. A hypothetical 750Ti and i3-4150T TDP is 95W combined, not including other components. Would they really need it all on the 12V rail though, as I've assumed throughout? I'm going to have to do some testing when I get bits on hand (run one or other, not both at same time). I could still go 1U PSU if modding this seems not worth the time.

Next up is a low profile cooler. I went for a Scythe Kozuti as it is not only low profile, but the fan isn't at the top so I don't have to fear about airflow restriction. The cooler is rated for CPUs up to 60W (90W at full fan speed), so at nearly half that it shouldn't have much problem. It will also be interesting to compare how well it does to the stock intel cooler, although one review suggests it isn't that different in cooling or noise if run at same fan speeds.

Finally I got 3m of orange electroluminescent string. No idea what for yet, but it was only a few quid...

 

[Porina]

Got a bunch of parts on hand now.

PCIe 16x riser. Looks ok so hopefully just works.
PicoPSU 160W - again not much to look at. Really does look small.
Leicke 150W PSU for above - this is a serious brick, like something from a laptop. They amusingly sent a mains cable that ends in those 2 pin connectors, not the IEC 3 pin one on the brick. I have enough spares so this isn't a major deal.
Scythe Kozuti - looks low profile but held against the stock intel cooler, it is perhaps 5mm shorter and you'll likely need more that to allow air to flow through it. So if it was worth it depends on the noise and cooling ability.

 

[Porina]

Finally getting around to do the hardware testing. This is the host system, currently powered by an ancient Enermax 430W(?) PSU. Note it doesn't even have enough pins on the mobo connector! The fan is dying so it makes a noise, so I'm not going to miss it.



And here is the 160W PicoPSU to replace it. That's it... not much there.



The PSU is powered by an external power brick as seen on top of the case here. Note I also had to move the HD as the cable would have been short to leave it where it was.

It was interesting to do a before and after test on power consumption at mains with the old and new PSU. Running Aida64 stress test it was 55W with the Enermax, down to 44W with the PicoPSU. That's quite an efficiency saving. I just added the 750Ti and with only CPU loaded the power consumption was 52W.

I'm loading up on some graphical benchmarks which I'll run and see how the system copes with the power draw in that condition.

 

[Porina]

Got some numbers for power usage in various scenarios now...

Firstly I ran some benchmarks, starting with Catzilla 720p scoring 8040 overall. Next was SteamVR where I got exactly zero, but this isn't a surprise. Finally I ran FireStrike getting 3764 there. During these runs, power consumption of the system at mains varied from 80W to a peak of 100W.

Next for something more stressful... as mentioned before, default Aida64 stress test running (CPU only) saw power consumption of 44W or so. I got out Prime95 and 4 threads of small FFTs bumped it up to 65W consumption. Back to Aida64, running only FPU stress it actually touched 67W yet temps were lower, so is the power going elsewhere than the CPU? The ram perhaps.

Let's load up the GPU with FurMark! Fire extinguishers on standby... it wasn't that bad. System was taking 112W max at the mains with the GPU eventually reaching a stable 68C. Not bad... let's add CPU loading back in too. With one thread of P95 small FFT this went up to 122W, and a 2nd thread hit 134W. I decided to stop there as at this point, I have no idea how close I am to the PSU's rating of 8A on 12V rail. So that's 96W on 12V rail output side. I have no idea on the brick efficiency to estimate what's going on there.

Next step, to replace the CPU cooler with a different low profile one and see if that helps temps/noise.

 

[Porina]

Finally retrieved the BBC B. Initially I plugged it in just to hear the startup tones, but this didn't last long. After doing this several times I heard a crackling noise and unplugged it quickly. Smoke made its way out, smelling like burnt paper. Don't know what had gone, but I know enough once the smoke escapes, it is impossible to get it back in again.


It was easy to take apart, just a bunch of screws. Here's the original board that makes up the computer. To the left is the compartment that is a power supply.


With the original board removed, here is a quick size check with the donor parts. There is enough height, but the cooler isn't ideal as airflow would be blocked by the lid. There's only like a few mm gap which isn't enough for airflow. An idea I'm debating is to cut a vent into the base, and mount the board upside down. I will also see what other cooler options there are. As a last resort, I could go back to the stock Intel one.

Note the mobo goes under the keyboard here. The GPU doesn't have to go under the keyboard, so that space is occupied by a SSD. I haven't decided on the orientation of the mobo. Do I want to cut the back and expose the backplate directly? Alternatively, I could put the backplate into the partition to the PSU compartment, and run cables into that. It would be practically hard wired as you wouldn't be able to access that without taking the lid off.

As a bigger question, I guess I need to decide how authentic I want to go. Do I want to keep it as original looking as possible? Or, if I say no to that, what more could I do? A window on the top? Repaint it? If I start modifying it, it would primarily be some kind of Elite 1984 theme, secondarily ED.


The keyboard... originally I was going to reuse it, but on pressing the buttons, I fear the workings may have corroded and degraded. Some of them feel wrong. It will be a big job, but could I replace the switches? Or find a near compatible keyboard to modify the keycaps onto? I suspect it is too different for any modern keyboard to fit, unless I want to totally modify it, which might be a step too far.

So... a start for now, but it could be a long time to get further...