WARNING: Long thread. This is mostly for the search engine and future reference.

I have been researched/designing/purchasing parts for a car PC for almost 4 years. When I first had interest in a car PC the only option was full sized ATX parts neatly hidden in custom fabricated cases, etc. Now with mini-ITX and nano-ITX (if they ever release the boards), it's a whole lot easier to build a nicely integrated car PC.

There are a LOT of pitfalls to watch out for. Think about all the things to consider when building a home PC, and then add in a billion more and you have all the things to consider when building a car PC.

First and probably most important: power, power, POWER. You would THINK this would be an easy part, considering PCs use 12V (and 5V) DC power internally, and your car puts out (theoretically) 12V DC power. Unfortunately, your computer needs a nice steady (regulated) 12V power, and if you ever look at a 12v voltage feed from your car, it's fairly erratic (no, not erotic). Secondly, car PCs are nice and all, but if it drains your battery, that's a pretty big bummer.

Solution: DC-DC power supply and a shutdown controller. The DC-DC power supply takes a voltage input feed from your car, cleans it up and sends it on out to the mobo, drives, etc. Some of them even provide an additional 5v lead for powering USB devices and LCDs. It takes two inputs, an input from your battery and an input from your ignition. It has one output, a two pin connector that connects to the pins where your case's power button would usually connect. Depending on how you configure the shutdown controller (often with jumpers), when the voltage on the ignition input goes to 0v (you turn the car off), it simulates pressing the power button on our case, thus shutting your PC off. Often times they will also have low battery failsafe cut off, so if for some reason your carPC does not shut off gracefully as it should, it will do a hard shut down and turn off the PC all together.

The next big thing with power are AMPS. You need to have enough amps in your 12v and 5v rails to allow for all of your parts (mobo, processor, PCI cards, memory, drives, etc) to properly work. This is where most problems occur. People get PSUs that do not put out enough juice, and then wonder why their car PCs are doing all sorts of weird stuff. My suggestion: go as powerful as you can. If you feel comfortable with not having the PSU within the car PC case (in essence an external PSU), do that and go as powerful as possible.

Pentium 4 processors are HUGELY power hungry. It's going to make the entire project MUCH more difficult if you want to run a P4. It's not impossible, but it's harder. I know this from personal experience. Pentium M's are better, as they consume a lot less power.

Display: Most people go with touchscreen Xenarc and Lilliput LCD VGA screens. I personally have a Xenarc 700TSV and I think it's the hottest thing since ... something hot.

Video: This is probably the trickiest thing to consider. Most LCD VGAs (like the Xenarc 700TSV and Lilliput) have a native resolution of 800x480 (widescreen). Now go to your computer's display settings and try and set your current display to 800x480. Ain't gonna happen. Unfortunately pretty much NO video card has 800x480 built into it's onboard chipset that stores the capable resolutions. AND WITH THE EXCEPTION OF A SELECT FEW ATI CHIPSETS (R200 or R300, I forget which), THERE ARE NO ONBOARD VIDEO CONTROLLERS THAT WILL SUPPORT THE 800X480 RESOLUTION. Period, end of story, do not pass go, do not collect $100. I know this and learned this the hard way. Ultimatley, look for a car PC solution that allows you to have at least ONE PCI slot, so you can add an inexpensive PCI card that allows you to use Powerstrip. Powerstrip is a free application that allows you to tweak PCI & AGP video cards (NOT ONBOARD VIDEO CHIPSETS) to that some may display 800x480. ATI Radeons are pretty good about this.

Cases: This was by far the most frustrating part. Finding a case that allows you to have an internal DC-DC power supply, shutdown controller, a PCI slot (or two) a case, memory, slim CDROM and a HDD (at least a 2.5" laptop one) that is not mammoth in size (at least in my opinion) is near impossible. The easiest and most flexible size is going to be the "cube" type/size cases. These allow you to install a PCI card standing vertically, usually a standard 3.5" hdd and sometimes even a standard CDROM size. Power supplies are easier to fit in these cases and they often times can come with 150watts+ power supplies by default.

The smaller the cases get, the more functionality you are going to lose, and the selection of compatible hardware is going to drop off too. For example, there is an "Ampie" case (also known as a voomPC) that has dimensions of 210 x 254 x56mm (WxLxH)... one of the smallest cases available. Unfortunately, it does not fit PCI, and the onboard video controller will not do 800x480, and you are limited to VIA mini-itx boards.

I have opted for the OPUS Vehicle Mini-ITX case. Has a built in 150 watt DC-DC PSU with built-in shutdown controller. Supports two PCI cards (mounted horizontally courtesy of a riser card) and with a VIA M12000 board you can have a PCMCIA slot too (important if you want a GSM-based internet service as most of them only offer laptop PC cards and not USB modems).

Suspend to RAM: This is often called "S3". It allows for faster shutdown and start up as it suspends your system to the RAM rather than the hard disk, then powers the machine down, yet provides just enough juice to the RAM sticks to keep their memory alive.

USB and suspend: I have yet to experience this problem, but it's fairly common, so I'll list it. Many USB devices are fairly cranky when it comes to going into suspend/standby and coming back out. Some USB devices will prevent you from going into suspend, some of them simply will not work (or appear as if they are not connected) when you come back out of suspend. This is something you'll have to play with. Try different hardware, do searches on forums before getting hardware.

Sound: Make sure your motherboard has a "LINE-IN" port. This is not the same as a MIC in. This is important, otherwise expect to be purchasing a USB Sound Blaster device to add a LINE-IN. If you plan on doing any sort of audio input into your car PC, this is key. Most motherboards come with this on it, but check none the less.

Cooling: Be sure where you place your car PC gets adequate ventilation. Note where the hot spots on your case are, and where the fans are, and plan appropriately.

Hard Drives: Go with laptop 2.5" HDD when you can. I know they are more expensive, but they take bumps and shakes a lot better than their bigger cousins of 5.25". In addition they require less power (and remember, power is key and in short supply!). Personally, I have decided to go with a 2GIG compactflash card. I load XP onto this card, and install everything else on 60gig 2.5" laptop HDD that I connect via USB. I have that hard drive at the front of my car (USB cable running to the trunk). As I have a subwoofer, I thought it would be easier on the PC if the hard drive with the moving parts/platters was away from the shakes of the sub.

Front Ends: There are like a dozen front ends. Go to mp3car.com 's message boards and decide which one you like. PErsonally I like Centrafuse or FrodoPlayer.

I think that's about it. There are some obvious things like having a 802.11 wifi device so when you pull into your driveway/garage you can grab stuff from your network (mp3s, etc). Bluetooth is awesome for a keyboard/trackball because it's non line-of-sight, so it's better than Infrared, and it can be used for multiple things, unlike if you get an RF keyboard/trackball (the RF sender/receiver is only used for that specific keyboard/trackball).

I'll post more if I think about it. Other comments are welcome!

 

www.mp3car.com/forums is also a good reference, but a somewhat unfriendly atmosphere. Before you ask any questions there, ensure you do a good search for the answers, or the only reply you'll get is "Use search, n00bz!"

Otherwise, it is a very helpful board, and I highly recommend it if you are planning on doing a CarPC install.

I will be shortly, myself, as soon as I get back from Iraq, and god_of_cpu comes out with the mount for the '05 coupes and the Xenarc screen. My plan is to use a small form factor PC (like AOpen, or Monarch Hornet) with a Pentium M CPU (low power draw) and an Opus 150 watt DC-DC power supply that includes the shutdown controller.

Dave

 

Problem with the small form factor PCs (like those at cappucinopc.com) is that they often times do not:

I am not familiar with the two you named. However, I decided to go the way of the VIA boards because of compatibility and standardization. When you go towards the custom form factor PCs, you quickly lose standardization. The one I purchased from CappucinoPC really would not work well in a car environment. the size was awesome though, about the size of a box of kleenex. Most custom small form factor PCs

1. do not support S3 suspend
2. do not have standard pins for power button on the motherboard (makes integrating a shutdown controller much harder)
3. do not have onboard video capable of 800x480
4. do not have expansion slots for adding video that does support 800x480

If these are solved by the two you mentioned, please let me know as I'd love to look into them for myself.

Thanks for the excellent feedback, I forgot to include outside sources of reference

 

I'm talking about small form factor on the size of a Falcon Northwest Fragbox, a Shuttle, etc.... Not the super small, mini-itx boards, but micro-ATX with generally standard motherboards.

www.monarchcomputer.com and click on Monarch Hornet for their version of a SFF

Others are easy to find as well.

1. The S3 suspend I am not sure about
2. The power button is standard ATX style
3. Onboard video I don't care about, because the boards have PCI-E slots, and I plan on putting an ATI x300, powerful to handle most anything I would do on a CarPC, yet not a huge power drain like an x800 would be.


But yes, the really small ones (cappucino, etc...) do have the problems you stated.

Dave

 

Oh, you are talking about a full ATX board? The Hornet looks like an ATX cube.

 

Well, yeah, but they aren't full ATX boards (I think) They are generally smaller, and those are usually whats referred to as the Small Form Factor, especially in regards to LAN party type computers.

Dave