Hardware used

[Itchy]

i cant afford a hdtv so i wont be going down that route any time soon

[antistrange]

Good god man! That sounds like a bad power supply, bad motherboard (bad power cleaning circuitry) or bad RAM.

CPU: 70W
RAM: 80W
GPU: 50W
Hard drives: 5Wx2
Optical drive: 5W
RAID controller: 10W? (I know some intel controllers need 8W)
Tuners: 20Wx2? (pci slots cant supply much, so this cant be too far off)

Thats 265W, and those should be peak wattages. I could see a poor 350W PSU struggle to provide stable power, but a nicer 350W should have done fine. 850W is enough power for a 7900GTX SLI gaming rig.

[gEd]

antistrage: Itchy is planning a low power mini-itx system with a low power epia cpu, that is presumably why the cases he has looked at use low power supplies. The figures you are quoting are for regular pc;s ---- hang on a minute, 80W for RAM!! shome mistake me thinks. maybe 25W for mobo AND ram

However I confess 90W does sounds low ! but I don;t really know anything about these epia machines.

Itchy: unless there are others here using these rigs, best check the manufacturers site(s) for advice on power consumption for your proposed systems. You should also heed Sub's advice, these machines are going to be borderline.. I don;t know what bits (if any) you have for this rig but it would be a crying shame if you spent lots of $$ on it, only to find it too slow for running gbpvr reliably.

[Itchy]

havent bought anything for it yet well i have the tv card but ive had that for 2 years now i think

main reason for the epia style board is the small form factor and slient operation. Ive only been playing with software so far so i can choose what i want to use on the machine before i actually buy the stuff

like you said i dont want to get stuck with kit that runs too slow im doing a lot of reading around the subject but the psu isnt something i have thought about

when i get back from work tomorrow i shall do some more research and let you all know how i get on

[antistrange]

gEd: I was more responding to daphatty and his power problems. Itchy seems so be on the right track even if he has not yet decided on parts. Yes, 80W for RAM. All the numbers I cited should be maxima. A pretty good rule of thumb for RAM is 10W/128MB, though DDR2 is more power efficient I think (daphatty was using an Athlon, so I assumed DDR). Overvolted, overclocked, high-performance RAM can consume a startling amount of power. Even standard RAM does require a fair amount of power, but yes I hope 80W is an overestimate (makes my point stronger if it is).
A carefully designed pvr could run on 90W, but be careful.

Itchy: I have done a bit of reading into the Epia and I just dont think it will be worth the trouble. You can get a lower clocked Athlon64 undervolt it and set up speed steppings. I have even heard, but not tried that RMClock Utility can create power profiles for A64s with Cool'n Quiet (I use it on my laptop, increased battery life by 20% on an already power efficient model). I think you would be surprised how little power and heat such a processor would use and it would easily be able to decode for an SD signal. There are many micro-ATX boards for A64 and they dont cost much. In fact the combination of A64 and uATX board may be less than an EPIA alone (havent checked the price in a while, but $170 for a good A64+uATX).

[gEd]

gEd: I was more responding to daphatty and his power problems. Itchy seems so be on the right track even if he has not yet decided on parts. Yes, 80W for RAM.

ah sorry, I missed that part of the thread.

80W RAM - No, sorry I can't let this go!

Think about it - a decent CPU will use 80W and look at all the heat that produces and the heatsink and fan required to dissapate all that heat. Where is all this heat from my RAM?, they are only warm too the touch.

My RAM runs at 2.9V. To consume even say 60W would require 20A!!

check this out
http://download.micron.com/pdf/technotes/TN4603.pdf

"Therefore, an SDRAM operating at VDD = 3.3V, with a
clock rate of 133 MHz, driving a load of 25pF would draw
18mW per DQ."

---

Anyway, good advice on the A64 setup and I agree that this is probably the way to go, although the A64 will still require a chunky heatsink and a fan, whereas I think that the epia chips can run passively with a small HS.

Itchy: You are absoluetly right to try and seek a small and silent setup but this is something of a holy grail...

Also, IIRC from one of Sub's old posts, the hardware mpeg decoder of the epia mobo's may not work reliably.

[antistrange]

Yay tangents!

Touch your RAM and then touch the heatsink attached to your CPU. They should be similar temperature. The reason you dont notice the temperature of your RAM so much is because it has so much extra surface area to begin with. It also produces heat over much larger area. The total heat output of CPU and RAM is likely similar.

To your link. As I understood that text (admittedly I did not read every word) a DDR266 128MB DIMM was found to require 620mW. This is assumed 100% efficiency I believe so its already a low guess, probably 1W total. Add RAM to 1GB is at least another factor of 8. Power consumption does not scale linearly with frequency so going from DDR266 to DDR400 is probably another factor of 3-4. So with these basic assumptions we are in the range of 32W already. I also noticed that the voltage cited was the older 2.5V DDR standard, most RAM today will use 2.7-2.9 (as you said). Power consumption scales as the square of voltage even in the ideal so a seemingly small voltage increase from 2.5 to 2.9 that you run is another 1/3 power increase. Now were up to at least 40W already. Make it high performance RAM that is overclocked (already less efficient) and overvolted you can make RAM draw a seemingly unbelieveable amount of power. Since daphattys sig doesnt specify, I assumed 80W to be safe.

I know it was an overestimate, but that was on purpose to be safe. The fact that it is an overestimate makes my original point for daphatty stronger. If the RAM uses 20-30W as we both hope, then his system should have been drawing just over 200W from a 350W PSU. Should have been no problem.

[gEd]

thanks for the detailed response antistrange. I know this discussion is not really helping itchy but it is a good example of the issues surrounding power usage in a pc.

BTW: If I left the fan of my cpu heatsink for a minute or 2, it would be too hot to touch.

cheers

[antistrange]

The only thing I might point out about your statement (though a good one) is that the spacing between fins on a CPU heatsink is almost perfect for insulating. The only reason the heatsink works is the fan. The air will stagnate between the fins without one, thus building up the heat. Check out the spacing on heatsinks that are designed to be passive. The fins are shorter, thicker, and spaced a bit farther apart. Because HSF are active, they can get away with the narrower spacing to increase surface area and thus increase cooling power. RAM luckily already has a nice fin shape so it doesnt need a fan, but try turning off your case fans and then touch the RAM (havent tried this part, now im curious). I also suspect CPUs are more efficient at converting current to heat due to high frequencies but I wont hold that as fact; ive never seen TDP listed for RAM.

I have now confirmed that RM Clock Utility can be used to undervolt and set up a performance on demand power profile for basically any CPU (the list got longer since I started using it). Any processor line like the A64 is set at a voltage that will operate 99.999% of the CPUs coming off the line. This also means the voltage is more than necessary for a great majority of them. In a mature CPU line like A64 they probably could lower the recommended voltage, but its too much of a pain to get the all BIOS changed. Take the A64 3000+ I recommended. It typicaly runs at 1.4V, but I wouldnt be at all surprisd if you could undervolt it to 1.15V (the mobile versions come in at 1.2V stock). This would take the stock TDP from 67W down to 45W. Much less cooling and power needed. The same would go for your RAM. As long as you test for stability, you could undervolt your RAM.