Heat questions

codeman · Post by **codeman** » Fri Jul 06, 2007 8:02 pm

Which of the processors on the N64 board gets the hottest? I'm going to have a temperature monitoring system so that the fan isn't on constantly, but I'd like to only monitor whichever chip gets the hottest in the least amount of time.
Does anyone know off hand which one gets the hottest and what a good upper threshold temperature would be?

ghosstt · Post by **ghosstt** » Fri Jul 06, 2007 9:02 pm

PM bacteria. im pretty sure he did something like this where he checked the temps.

bacteria · Post by **bacteria** » Sat Jul 07, 2007 12:17 am

No, I have no idea how hot the chips get, but I know from research that the chips get very hot and are designed by "N" to tolerate a lot of heat (hence the metal sheets in the N64 as heatsinks, which don't have any fans).

Problem in a portable is that you want everything cool as whilst the N64 mobo has toleration of heat, your other parts won't in there, which includes the fact you are holding the unit (and it is better everything stays cool).

No, I am keeping the fan on constantly whilst the N64 is on, using heatsinks (which you need anyway for the processors) and will incorporate good airflow - can't do more than that!

Ensure the fan is really quiet. Some people have used small fans in their N64, however they (research again) seem to be about 26dB - 32dB, which is a noticeable volume (and a bit annoying). Larger fans can (some at least) go to 9dB but are 25mm thick - mine is 60mmx60mmx25mm; I also have a 80mmx80mmx25mm one as quiet, but it is a bit big. 15mm thick fans can be 17dB which might be quiet enough, i'm not sure, going to get one to find out - would make the final case less deep! There is no issue with keeping a fan on all the time, because 1) they use very tiny amounts of power, 2) can last over 2 years on constantly (long life) and 3) better a constant noise (if there is one) than an intermittent one (less annoying).

Go for a really quiet, silent, fan and keep in on constantly is my thoughts.

codeman · Post by **codeman** » Sat Jul 07, 2007 5:05 am

I have heat sinks on everything, and I have a fan too. It's a little louder than I would like, so I'll probably get a different one. But I'm really just trying to get some power savings. The fan will take about 50mA or so, maybe more. So I'd really like to save that power when it's not needed to keep the processors cool.
If I can cut out 10 minutes of the fan being on, that adds 10 minutes to how long the backlight of my screen can be on. Know what I mean?

bacteria · Post by **bacteria** » Sat Jul 07, 2007 6:06 am

The screen (PSone) takes about 750mA (unmodded), so therefore, if your fan is 50mA, it won't make much difference having the fan on all the time. Anyway, if heat builds up in your case, plastic might melt (eg case, etc).

This isn't an issue on my project however, as I am using mains.

timmeh87 · Post by **timmeh87** » Sat Jul 07, 2007 9:30 am

If i had to guess, Id say use the main processor as your temp. reference. Its clocked 150% higher than the GPU. Im just going off of my PC experience here, the cpu is fastest, hottest, and gets the most cooling.

It would be big the one to the left of the middle (cart slot on top, motherboard face-up).

the one above the ram is the coprocessor (GPU).

I actually recall reading something on how the main processor dosent have DMA which is pretty weird...

Post by **marshallh** » Sat Jul 07, 2007 10:03 am

The r4300 CPU doesn't have DMA, it just tells the RCP to DMA in bits of the cartridge to RDRAM. I might be wrong though. I'll look through the docs in a bit.

I'm pretty sure hte RCP gets the hottest, it's rasteriziing the entire scene into framebuffer while all the CPU does is to feed displaylists/textures into the RCP.

codeman · Post by **codeman** » Mon Jul 09, 2007 9:03 pm

Yeah, the RCP chip defintely gets the hottest. But as for my other question...does anyone know a good threshold temperature to check for? I've decided that I'm going to have the fan on the whole time, but I'm going to vary a PWM duty cycle based on the measured temperature from 50% to 100%. I'm going to have "trip points" that will change the duty cycle to 60%, 70% etc. when the temperature is within that range (with a hysteresis effect in case the signal "bounces").

Any suggestions on what my temperature levels should be?

timmeh87 · Post by **timmeh87** » Mon Jul 09, 2007 10:31 pm

just guessing here but 60 degrees C sounds reasonable to me.

bacteria · Post by **bacteria** » Tue Jul 10, 2007 2:18 am

Yes, if the temperature of the CPU in a computer gets much higher than this, you can start to get problems, so I guess it will be similar on this board.

60 degrees C is still hot, might be hot enough to melt or soften your case if it is fairly close possibly... (so might be a good idea to have the temperature lower).

codeman · Post by **codeman** » Tue Jul 10, 2007 6:47 am

Yeah, I'll definitely put it lower. I just wasn't sure what the failure point of the chip might be. But I'll work with somethign less than 60C as my upper limit, Thanks