Underclocking an AMD A8-3820

[BiG K]

Here is the deal, I have a computer set up in my car. I was using a VIA C7 1.5Ghz (~24w TDP) on a stripped down version of Windows XP which was working just fine for over 4 years however it was a tad bit too slow for videos, which I didn't really care.

So an upgrade was on the cards, I went for an AMD E-450 (~16w TDP), on the Asus E45M1-I Deluxe. I have to say, it's pretty damn fast, except I can't customise Windows 7 as I did with Windows XP so everything isn't as fast as I hoped it would be, even though I have a Corsair Force 3 SSD, while I was using a traditional 4 year old 2.5" Hard Drive in the old system!!!!

So I want to upgrade again, even though the "new" system has only been in the car for a few weeks lol

So I have picked up an AMD A8-3820, which uses 65w TDP. I need to get the power draw down as much as possible, even though at 65w TDP, it shouldn't present a problem, it's just that I sometimes listen to music with the engine off and I don't want to drain the car battery too quickly (PSU has a fail safe to turn the system off at 11.1v). Technically I don't even need a quad core as a single core will be more than adequate, however I went for this chip because it's the most powerful available at the lowest TDP available in the Llano range. I will be using this in conjuction with a AsRock A75M-ITX Motherboard. I don't have the motherboard yet but should have it in a few days.

Question now is, is there anyone that can guide me into reduicng the power draw as much as possible?

P.s, I don't care about what Intel has to offer, I hate Intel, so I don't really need 2 million posts about how an Intel will be better. Infact, I would rather install a dual battery system just to power up my AMD computer if needs be! lol

P.p.s I used to overclock my AMD K8 series (Barton 2500+ hell yeah!) but I have figured out that for average usuage, processor speed doesn't matter and while I game, I buy the best graphics card I can and just leave the processor. (once had dual 8800GTX's on a AMD 3500+ single core......) So I have no idea what tweaks I can make to the system, as I have been out of it for so long!

 

[sm625]

Why not just use a notebook? Preferably a cracked screen craigslist deal...

 

[Xpage]

Well you can get low voltage DDR3 to drop the power draw a bit, as well as an efficient PSU, unless your current PSU will support ~45W CPU from your 25W usage. I'm assuming you can drop the usage by about 33% or so. However most of the time the CPU will be idle, so you will only need to worry about power draw under high loads.


Power usage scales to the square of voltage. Thus lowering your voltage is key, I'd see what the lowest voltage you need to keep your default settings are. Then drop your CPU multiplier, then drop voltages again and see if it is stable. If not drop GPU frequency, see if stable. If not, then drop CPU more. repeat.

At some point the minimum voltage will be reached, unless you want a 400mhz llano at 0.5v. I'd pick the best performance (mhz) per volt and use that. Most of the time the CPU will be idle.

 

[KompuKare]

A broken screen notebook would be a good alternative although I assume you have a nice ITX case. As regards underclocking all I can suggest is hooking it up to a watt-o-meter and watch the draw as you see how low you can go frequency wise. Looked that manual for that board I didn't see any option to disable cores so frequency is all you can try for the CPU. Hopefully you can reduce the voltage once your frequency is low enough. Llano power gates really well so that helps too (and means you'll have to load the CPU 100% at each setting to find the max draw). And don't forget the impact onboard devices can have (disable everything not needed) and RAM voltages etc. (although you probably have to have picked your RAM for low voltage to begin with).

And I don't think Intel's options for this would be any better. Atom is way too slow and something like the 2400S is fairly expensive for it is.

 

[Cerb]

What customizations are lacking in Windows 7, such that the E-450 won't do?

 

[BiG K]

Thank you for all the input on this guys, I really do appreciate it.

I don't want to use a cheap notebook as I do indeed have a very nice mini ITX case, a Voom PC. Plus I often lug around alot of bulky and heavy goods, the current case is made from 5mm thick extruded aluminium, so it is VERY tough. I wouldn't have anywhere to mount a laptop either as I don't have anywhere to mount a laptop.
Netbook would be an equally bad choice as I already have a Netbook processor and just wish for a little bit more speed.

WinXP vs. Win7. - With Windows XP, I used nLite to absolutely strip out anything that wasn't neccesary, such as System Restore, printer spooling and so on and so forth. It was incredibly stable, it didn't hibernate properly maybe once every 3 months and that was it. I could depend on that machine to provide me with the entertainment I needed. With UK roads so badly congested, it is such a relief to just pull over into some services when the traffic is bad and watch a movie while everything calms down!
However Windows XP can't be used on newer systems and I just can't strip down Windows 7 as much as I did with Windows XP. For example, if my computer hangs on boot up, I will cut the power and start it up again. Windows Recovery will immediately pop up to try and detect any "problems". It won't find anything and I have just driven around for 15 minutes waiting for that thing to disappear! I don't want UAC and whilst I have disabled as many services as possible, it doesn't boot up very quickly and it just doesn't feel as "snappy" as Windows XP on the Via C7 did, even though the processor is much better and Win7 is on a fast SSD whereas WinXP was on 50mb/sec hard drive!

The power is handled by an 160w M2-ITX, A DC-DC power supply unit that is 94% efficient on 50% load. It was designed to power an Intel P4 lol So this is as efficient as it will ever get.
There aren't any accessories connected, just a 7" touchscreen monitor, bluetooth dongle and USB hub up front.

Low Voltage DDR3 - I already have the RAM, plus Low Voltage ram only saves 1w on average, something I can easily acheive by dropping the speed from 1600Mhz to 1333Mhz, with a corresponding drop in voltage and SPD timings

I think I will drop the processor to 1Ghz and see what the performance is like, if it is adequate, then I will drop the voltage/multiplier to suit the speed that I find to be adequate.