Help me with TEC temps

[noskill]

Well, here's what I have:

P4 2.6 Northwood @ 2.6 (this is just crap, I'm trading it into 3.0 Prescott)
R9800 XT

CPU is cooled with Swiftec MCW5002-PT (226W)
GPU is cooled with MCW50-T (80W)

Ambient temp is about +28-30C.
CPU temp after idling for 10 minutes reaches -10, sometimes -11 (it drops fast to -8, but then it needs some idle time to go for -11). Load temp is +10 maximum.

When stock R9800XT heatsink is used, RivaTuner shows me +58-65C. With MCW50-T, idle temp is +38, load is +42-44.

Now, we all know the following formula:

DeltaSides = (1 - (PowerGeneration/TECPower)*69)

So, DeltaSides would be: (1 - (70/226)*69) = 47.6C. I assume heat generation is 70W, if I'm wrong, please tell.

So, if we're idling at -10 and difference between sides is 47.6C, then coolant temp would be +37.6C. OK.

Now we calculate vice verse, power generation for GPU. Note that I'm using 67 coefficient instead of 69, since they differ for Peltiers in CPU and GPU.

Coolant is +38 and GPU is +38. Appears like MCW50-T makes 0C difference between sides and just keeps GPU temp to coolant temp. Luckily, it is not underpowered, so GPU won't burn. Since Peltier has ~75% efficiency, approx GPU heat generation would be then about 60W.

Now please tell me if I'm wrong with my assumption. If I'm right, then how do you guys work this out? Put better Peltier? I was able to find 180W Peltier on DangerDen, but it is rated 24V, so I would need to buy Meanwell 640W PSU, which is no-go for me ($200+ kinda sucks).

Any ideas on my TEC temps? Should I throw this crap out of window, or it is okish?

[saaya]

i dont understand what your trying to calculate :confused:

your cpu is probably around 70W under load, thats correct, but you said your load temps are +10°C. this means the hot side of the tec is 57.6°C

in idle the cpu produces much less heat, probably only 40W or less i think. that means idle delta is:

(1 - (40/226)*69) = ~55C delta.

so in idle your cpu temp is -11°C wich means the hot side of the tec is probably around 44°C.

yeah, you need a better tec for your card if you want low temps and your power assumptions are pretty much what i think. the tec is less efficient that 75% though, so i think the 9800xt gpu puts out ~50W


about your cpu temps... is it all one loop? what is the water temp? 38°C? thats a little high! and the cpu tec is not getting its heat removed that well. this is a problem of the block not performing very well at removing so much heat.

you can either upgrade and get really nice and low temps and ocs, or you go back to normal watercooling and get worse temps but get money for selling the tec stuff so you can buy new hardware.

or, you go for phase changing the cpu and use the 227W tec in your mcw50-t to cool the gpu.

what radiator do you have? with what fans? what pump?

if you want to stay tec i would recommend you to buy an iwaki or lookalike pump for 100$+ and sell your current pump, so thats 80$.

how are you powering the 227W tec? if you have a dedicated psu then do this:

buy a 320W tec from ebay (pm kris aka freecableguy, he bought one recently) and use it in your cpu block. then put the 227W tec in your mcw50-t block (make sure its a 40mm tec! if not then get one from dd for 40$ or try to get it cheaper on ebay).

if you dont have a dedicated psu then buy a second 227W tec for the gpu.

third and most important! you need another rad! i suggest the dd dual heatercore for 35$ plus at least 2 high pressure delta 120mm fans (push a lot of air even at low volts and are almost silent at 5v!)

so thats 80$+ for a new pump , 30$+ for a 320W tec or 30$+ for a second 227W tec, and 35$ plus at least 2 deltas for 15$ each so 65$.

80
30+
65+
----
175$

for less than 200$ you should get -15°C or lower for you gpu and more or less the same cpu temps for your prescott (remmeber prescotts run HOT!)

if you dont have a dedicated psu to run a 320W tec then id recommend you to get a northwood instead! they run 20-30W cooler at the same speed, and your 227W tec will have a hard time to cool an oced overvolted prescott! a very hard time!




btw i fixed your signature :D


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