help with pelts for videocard memory

[saaya]

i want to buy peltcool the memory of my radeon 8500 , is 8W enough? how much W should it be?

ah well, im planning to do the vmod on that card, so it will produce more heat than normally...

[Nohto]

Your best bet is go to the website of the memory manufacturer and look up the specs. I think that memory is Samsung, but i'm not sure.

[saaya]

no its hynix memory , they say it dissipates 1 Watt of heat :confused: ...i really dont think thats true. i know that ati is overvolting the memory to make it run stable, but 1 Watt .... id say its at least 5Watt...more like 10...

[KnightElite]

You might want to get a cold plate to cover all of the memory chips, and the GPU, and just put one great big TEC on the whole thing. I know Sysfailur makes cold-plates for video cards.

[saaya]

i just bought 6 28Watt peltiers (30mm x 30mm) 2 for the gpu 1 for 2 memory modules :toast: ive never built a pelt setup before, any links with howtos?

im planning to watercool them. i think the tecs on the memory dont need to run @ full power, how do i make them run with less power so they dont heat up the water unneccessarily? the default requierement is 6A 8,6V. will a 300Watt psu do the job? 2pelts on the gpu running the full 28Watt, the other 4 running 10-20 watt each? 56Watt is enough for the 8500 gpu right?

thx :D

[Nohto]

You can run them is series and that will cut the voltage in half for 2 pelts.

[saaya]

you mean connecting them to the 12v line they would all just get 6V? how can i make the two tecs on the gpu run @ full power and the rest of them run with less...is that possible after all?

[Nohto]

You would run the 2 for the GPU in parallel, and the ones for the memory you would run in series. (2 per run)

[KnightElite]

It will be fairly challenging to run them at 8.6V off a standard computer power supply, since your outputs are 5V and 12V. But as Nohto said, if you run them in series on the 12V line, just two of them, you will get 6V per TEC. This will give you 70% of the maximum cooling power (6V/8.6V).You'll need a pretty beefy PSU though in order to run many of them. If you run all of them this way, it will draw ~150W, but you'll need to make sure you can supply enough current to power everything.

[saaya]

if i let the memory tecs run @2.5v they would run with 30%=10Watt right? should be enough to cool 2 memory modules, what do you think? 40Watt for the gpu on the 12v line + 40Watt on the 5v line. thats only 80Watt, couldnt even my old 200Watt psu do that?

is 40Watt enough for the gpu? :/

[Nohto]

Remember that is total wattage. 12v+5v+3.3v=200w and most of the time power supply manufacturers lie about the total wattage. Another thing you have to consider is that the pelt is constant where as the comp PSU isn't rated for a constant load.

[saaya]

it says 200Watt max, 125Watt max on 5 and 3.3v and 75Watt max on the 12v cable. hmmm i think it can deliver 100Watt steadily w/o probs...right? well im sure it will do 80Watt....tell me if im wrong, i dont know s*it about pelts :p

[Nohto]

Melcor (http://www.melcor.com/)
You can go to that web site and they have links and important info. Also you can try searching Google for "Thermo Electric Cooling."

[Nohto]

1 pelt at 8.6v = 51.6watts
P = Power (watts or volt-amps)

I = Intensity (current in amps)

E = Electromotive Force (Voltage)

R = Resistance (Ohms)

[saaya]

dont get it :confused: btw the pelts i bought are 28Watt @8.6V

[Nohto]

I believe that they remove 28 watts of heat. I could be wrong, but Ohms law states to find wattage you take voltage x amperage to find watts. Hence 8.6(volts) x 6(amps)=51.6(watts)

[KnightElite]

Nohto is correct. The rated wattage is how much heat they move, the actual power consumed is Voltage x Current.

[saaya]

aaaaaaahhhhh ok got it! :D so they move 28Watt of heat, but they need 56Watt to run at all...

so all that pelts together would need 160Watts right? what psu should i use to power them? 235 250 or 300?

[Nohto]

Don't get a psu get a dedicated powersupply. My Swifty MCW50-T recommends using a 20A @ 12v and the 80w pelt pulls 7.5A @ 12v. You can pick up Power supplys at various places XTREME TEK WERKZ (http://www.xtwerkz.com/power_supplies.htm) PYRAMID REGULATED P.S. (http://www.calibex.com/serv/calibex1/serv/calibex1/buyer/OutPDir.jsp?node=&otherForm=n&doSearch=y&advanced=n&searchnodeid=-1&search=PYRAMID+POWER+SUPPLY) or search the O.C. shops.

[saaya]

hmm they are really prices here in europe from what ive seen... why shouldnt i use my old psu, or buy a regular 300 350W psu for 25-30$? is there really a big difference?

....plus the tecs i ordered are supposed to run @ 6A 7V...

[KnightElite]

Yeah, they will run at less voltage than their maximum rated voltage and give you a corresponding fraction of heat transferred

(current voltage/max voltage)*max heat flow = heat flow that you actually get.

You might be able to run them all off your current PSU... but it may not be able to supply enough current, and might burn out over the long term.

[saaya]

hmm all the tecs would need 160W, what psu would you say can handle that in the long term? a 300W psu should be enough right?

[KnightElite]

It all depends on how you hook it up. If you plan to run some of the TECs off the 3.3V or the 5V lines, and some off the 12V lines, you should be fine. If you're going to be running all of them off the 12V lines, then the PSU probably won't be able to supply enough current to keep all of them happy.

[saaya]

i was planning to hook them up differently since the ram wont tecs wont have to run more than 10W i think. ok some guy from another forum said i can short the 5v with the 12v to get 7v? is that right :confused: so if i let them run a certain voltage, will the psu automatically give them the amps they need?

do you think a 300W psu can supply all those pelts when they need about 200W all together? or should i get a 350psu?

[Player0]

Yeah, you can achieve 7v by connecting the positve side (red wire) of the peltier to the 12v rail, and the negative side (black wire) to the 5v rail.

The PSUs total wattage doesn't mean anything important. You need to know the amperage available on the 12v rail. Most 300w powersupplies will have like 12-15amps on the 12v rail, but check the specs on your particular PSU to make sure.

You're peltier draws 6a. So subtract that from what you have left on your 12v rail. So if you have 12a @ 12v, and you use 6a of that for the 7v peltier, you will only have 6a left on you're 12v line for the rest of the system.

(I'm not entirely sure on this...im pretty sure that if you wire the PSU with the 12v and 5v rails to make 7v, the peltier will STILL draw all 6amps of current from the 12v line, but it may be less. Im not 100% sure).

Anyway, if you DO power this peltier from you're systems powersupply, its the ONLY peltier you can power from it.

The other alternative is to connect the 6a @ 7v peltier to the 5v rail of the PSU. This will only give you 20W of cooling power instead of the full 28w. But it free's up your 12v line for a second small peltier.

[KnightElite]

I'm just trying to figure this out here...
if you take four of the TECs and run them on your 3.3V line, they will each be moving 10.75W of heat from the cold side to the hot side. They should all be parallel in order to do this, and your 3.3V would have to be able to pump out 10A, which the 3.3V line should be able to easily handle. You could use these TECs for the RAM.

You could then use 7V through each of the other two TECs by connecting the red TEC wire to the 12V on the power supply (yellow wire) and the black TEC wire to the 5V on the power supply (red wire). That would give you ~23W per TEC for the GPU, or ~46W total GPU cooling. You would want to wire these TECs in parallel. These should also draw a total of 10A, between the two TECs.

Hopefully that helps you out. Your power supply should be able to handle the load if you do it that way.

[saaya]

cool thx! now all i need to know now is how do i set them up in parallel? :D all red cables of the tecs connected to the same 3.3v line?