200W, mini-itx, what's the fastest system I can get?

[JonJ678]

The summer is getting ever closer, and with it the very real threat that my electricity bill will no longer be included in my rent. Current computer is somewhere around 500W and spends most of its time folding, I've somehow convinced myself that the tenner a week in electricity justifies buying a low power computer. However I'm having considerable difficulty choosing a specification, so I'm hoping you kind folks can help me out.

I have a budget of around 150W for mini-itx motherboard, dual core cpu, ram and graphics only. Not gaming in the sense these boards usually take it, but I'll be annoyed if it's incapable of running age of empires or morrowind.

There are a few options that I've found, but none seem quite right.

1/ Atom + ion, comes easily under the wattage limit but is very slow
2/ i3 + intel H55 board, within wattage limits, fast.
3/ i3 + zotac H55 board, limited overclocking, infamous aftersales support and fair chance of mortality.
4/ E8400 + intel/zotac board, much as above two options
5/ i3 + dfi P55 board, great if I can get discrete graphics within budget
6/ J&W am2+ board, dual core amd. I very much like the board, but it's not very power efficient and I don't know anything about amd processors

Budget isn't too much of an issue, but I want this to be small, fast, quiet and reliable. It should be easily possible to get these four components for under 400. I'd appreciate any input you can offer, especially from those knowledgeable about the amd half of the field.

The mac mini offers a 2.26ghz c2d, 2gb ram, nvidia chipset for 500 quid. This is pretty poor value for money imo, so that's out unless they introduce i3 based ones in the near future.

 

[JonJ678]

Low power means I can run it off a dc to dc board rather than an atx psu, which means one less fan. Similarly low power consumption means the fans I do need can turn slowly. Both are good things for what is basically a htpc.

i3 with h55 sounds spot on to me, except for the limited range of motherboards. Neither gigabyte nor asus appear to be planning any so I don't have much hope for an overclocking board aside from the zotac, which offers limited voltage adjustments to prevent it self destructing.

780/785 boards seem to be pretty much the same, the integrated HD4200 is rated as significantly better than the X4500 which, while rubbish, is just about good enough for my purposes. I'm trying to get my head around the energy efficient amd options, they seem to be the same as the normal parts but undervolted and underclocked which doesn't seem particularly useful.

Regarding the amd option, a comparison of the 720 and 705e tricores

From amd's website,
720 has a clock speed of 2.8GHz, a TDP of 95W, a vid range of 0.85-1.425V
705e has a clock speed of 2.5GHz, a TDP of 65W, a vid range of 0.8-1.25V
95*(2.5/2.8)=85W, so the clock speed reduction accounts for 10W
95*(1.25/1.425)*2=73W, so taking worst case scenarios for vid, dropping the voltage accounts for 22W

Google seems a little unsure whether the e version is an undervolted, underclocked normal version but it looks likely. There's not much in it as far as prices go, the 705e is slightly cheaper. I think an unlocked multiplier is probably more useful than a part binned for lower power consumption, so if I go for amd it seems I've found my processor.

 

[JonJ678]

Going to have to be mini-itx for various nonsensical reasons, which does make life somewhat more difficult.

A sensible choice would be an intel h55 board with an i3. A more exciting choice is a phenom tri core with J&W board, pricing seems similar. E8400 would be excellent if I could find an overclocking motherboard for it which doesn't have zotac written on it.

 

[JonJ678]

Nice one Hotwired, I've spent the last couple of hours digging through MM but still missed some of those. Cheers. There's a phenom 2 705e which also looks good.

I ran into that build a few days ago and couldn't think of anything worthy to say to it. I'm a bit worried for the health of your psu but peering carefully at the photos suggests it's not as starved for air as it first appears. Astonished that you haven't undervolted the processor, power consumption varies as the square of (voltage/vid) so just dropping it by a little bit will work wonders for your temperatures.

I'm struggling a bit with benchmarks and amd overclocking hints, but I think a J&W am2+ board with phenom 705e would be better than e8400 and the zotac board.

 

[JonJ678]

Yeah, and even those options appear to have vanished now. I've got a couple of guys I can ask locally who stand a pretty good chance of sourcing one from China, if that fails the 780G board is readily available and probably the same thing really.

Their forums aren't letting me register weirdly, refusing to send me an activation email. I'll try them again in a few days.

Sounds like we're on the same page mymorph. Pico psu should be more than capable of this if there's no discrete graphics card, bit of a stretch if there is.

 

[JonJ678]

Poverclock = Pstock * (frequency/stock frequency) * (voltage/stock voltage)^2

The power used at stock is ideally measured, but failing that the TDP (thermal design power) is normally taken as a worst case scenario. This is used in post 3 when wondering how the phenom 720 compares to the 705e.

If it's the MINIX™ 780G-SP128MB you have in mind I'm pretty certain it supports 95W watt processors but strongly recommends you use 65W ones to avoid massive overheating in a mini-itx case. Overclocking a 95W one without very good cooling on the mosfets is likely to kill it though. I've emailed their UK sales guy, so fingers crossed.

AMD
MINITX 780G-SP128MB for 105
Phenom 720BE for 100
4gb of sodimm ddr2 for 70

Intel
DFi Lanparty P55-T36 for 105
i3 530 for 90
4gb of ddr3 for 80

Basically nothing in it for price. A low profile, very weak dedicated graphics card is likely to outperform the HD3200 on the amd option anyway and should come under power budget, so inclined to go down that route instead. The zotac H55 board has surfaced at last, so choosing between that and the dfi is tricky.

Cancel my last. Turbo boost doesn't work on it, the azurewave wifi card they're using is rubbish, and their x16 pci-e slot is incapable of working with pci-e x1 cards. Zotac are dropped from the list again. Potential graphics card here, the 5450 in a passive, low profile version, drawing 20W under load. From 40 quid ish, depending on what type of ram.

DFI board is likely to kick the bucket when the processor draws around 125W. The 750 has a tdp of 95W, a maximum vid of 1.4V and a frequency of 2.66. Making a reasonable guess that 3ghz @ 1.2V is possible, this would be about 80W load. 20W for the gpu, a blatant guess of 30W for the motherboard, 10W pump, 15W hard drive, 5W fans is 160W. Not a whole lot of clearance from the pico, but it's within possible limits.

 

[JonJ678]

Nah, I've already tried matx. It didn't go well, ended up moving to a full size case. It looks like mini-itx motherboards are capable of everything atx ones are, except for the single expansion slot of course. The main thing is whether I can get away with a pico psu or if I'll need to use an atx power supply. I think this means buying components, assembling them and testing before sorting out a case.

Definitely interested in your 555's results. Undervolted + overclocked is a brilliant combination. I'm a bit thrown by the triple/quad core power consumption being similar, it seems the dead/switched off core still uses some power.

Currently leaning towards the following specification, in the spirit of no half measures,
DFI Lanparty P55-T36, £105
i5 750, £160
4GB 1333mhz ddr3 £85
Sapphire 5450 £45
Pico psu £30
216W AC adapter £30
So £450 new. I'm not really in much of a hurry so should be able to get the processor and ram second hand bringing the price down to below 400. Criticism more than welcome.

Power consumption for the 750 here, suggests 130W load at stock or 110W undervolted, other hardware is an atx P55 intel board and a 9400gt. Pushing the limits of a 150W pico pretty hard (think it would be running over rated spec).

 

[JonJ678]

Fold on it? I imagine I'll end up doing so, certainly seems like something I'd do. It'll be replacing the missus laptop which is quite rubbish and now dying, so that when she gets back from a hard day trying to be a lawyer she has a computer that runs flawlessly to reduce anger. I want it to be quiet for the purposes of watching films and playing music, and also that noisy computers annoy me. 750 is probably a bad call.

That's a very, very good post Hotwired. With luck I should be able to go one better, I've borrowed a current clamp from uni. It'll tell me the current running through individual wires, accurate to about 3%. Given I know what voltage each line is at I'll then know what wattage each part is using. My psu is sleeved unfortunately, so I'm going to buy a set of extension leads and measure the current down every one of the internal cables of my computer. Fingers crossed I can get a complete set. Not that I've managed to work out how to use it yet mind.

Interesting point on cpu vs gpu wattage, need to have a think about that one.

 

[JonJ678]

Clamp is definitely capable of DC, intended for currents around 50A or so meaning accuracy won't be as good as using a multimeter. A lot easier though. Showed 1.2A for my pump which is about right, but can't get readings from the rest of the hardware yet since all the wires are sleeved, and the magnetic field around three 12V and five 0V wires isn't going to be terribly informative.

The pico is very high efficiency, 90ish or something daft, but you're right in that it doesn't include the efficiency of the mains ac to 12V conversion. Efficiency of the brick is somewhat variable, 75 to 90ish depending on which one you get. The pico is also rated in terms of output currents, so the nominally 150W pico needs a 180W brick to operate at full capacity. The DA-2 is around 83%. I'm concerned that the 12V will be excessively variable and lead to lower overclocks, but not sure there's anything to be done about this.