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Help with tuning an SS Unit

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MaddMutt

Member
Joined
Jan 12, 2015
I'm posting a big question on this as I have some understanding but not all :facepalm:
1) How do I know what the SS unit's heat load is?? 200w, 350w all I have is my benching computer for tasting. i7-8700k (de-lidded/direct die no IHS) EVGA z390 Dark MB (max on board CPU temp is 0c - 100c)
2) Does the Cap tube length or Does the Size of the Condenser = how much a heat load it can handle?
3) I have benched my i7-8700k and have observed the following... The Max Cold -35c, Idle -32c, Load -25c (Load was 2 Min of 1080p/4k HWBot x.265 @5.1GHz AVX) The CPU reached a Max temp of +35c.
I do not know if I need to have it re-gassed, this is normal, you are going to damage the compressor because of xxx.
I have included pictures of my SS unit and a basic diagram of how a SS works.
I have thought on taking it to my local HVAC but do not want to be told - Your problem is that when the Liquid (R-134a) turns into gas @ the Evaporator it now has 1.21 Jiggawatts and you need a Flux Capacitor @ the Condenser to return it back to a liquid - OR Your Compressor is only a 1/3, 1/4, 1/2 HP and you need a 1, 2, 4 HP rated one to run/make/cool properly.

Thank You For Your Time :)
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Mr.Scott

Beamed Me Up!
Joined
Jun 9, 2013
Condenser is very small and only a 1/10th HP compressor. You won't even see 200w with that.
My chiller gets better temps. :p
 

dejo

Senior Moment Senior Member
Joined
Nov 11, 2001
that SS is very similar to my SS. Temps on mine basically do the same- when under a sizable load, my temps will go positive by quite a bit. I havent used mine any anything newer than my old 6700k and dont really recollect the actual temps that I saw. Know that temps are still temps at the cpu. So at 100c the cpu will start to throttle.
I also would guess that the temps arent the actual temps at the IHS, as mine always stayed frozen there. My assumption was always that the cpu cant push all the heat to the cold plate with enough efficiency to keep temps from rising above freezing
 
OP
MaddMutt

MaddMutt

Member
Joined
Jan 12, 2015
Thank You for your quick and knowledgeable response :) I'll keep it as a possible GPU cooler. I will save up again and hope to purchase a better SS unit. This is a 3rd/4th hand model and I had to put a copper shim (A copper add-in plate for HD-7970 generic water blocks) on the die so that I got uniform cooling. I had several days of remounting as I had temps from coldest-hottest cores (6c/12t) of more than 10c. I love the fact that I can go hours on benching and not have to mess with refilling the POT or Winter for the cold air.
@ dejo - I would have gotten yours but the wife refused to drive to ~ Dallas, TX to pick it up :-(
 

dejo

Senior Moment Senior Member
Joined
Nov 11, 2001
No biggie, glad you got something to work with though. They are fun in that you can just go and not be too interrupted in the middle.
 

makaka

Member
Joined
Jan 5, 2004
Location
home
1) How do I know what the SS unit's heat load is?? 200w, 350w all I have is my benching computer for tasting. i7-8700k (de-lidded/direct die no IHS) EVGA z390 Dark MB (max on board CPU temp is 0c - 100c)
Use hwinfo64 it usually show cpu power usage
2) Does the Cap tube length or Does the Size of the Condenser = how much a heat load it can handle?
captube is used to optimize for load , the longer it is the lower the temp but the lower the capacity .
shorter captube mean more capacity but worse temp .
the condenser size should be enough for all the system load + compressor power .
so if your cpu use 200w and compressor use 200w , then the condenser need to remove 400w with acceptable delta T .
You have to check the condensing temperature right at the exit of condenser to see how well it is performing ,
in general if refrigerant leave the condenser with a max of +5c (above room temperature) it is considered good , condensing at room temperature is perfect .

3) I have benched my i7-8700k and have observed the following... The Max Cold -35c, Idle -32c, Load -25c (Load was 2 Min of 1080p/4k HWBot x.265 @5.1GHz AVX) The CPU reached a Max temp of +35c.
I do not know if I need to have it re-gassed, this is normal, you are going to damage the compressor because of xxx.
I have included pictures of my SS unit and a basic diagram of how a SS works.
I have thought on taking it to my local HVAC but do not want to be told - Your problem is that when the Liquid (R-134a) turns into gas @ the Evaporator it now has 1.21 Jiggawatts and you need a Flux Capacitor @ the Condenser to return it back to a liquid - OR Your Compressor is only a 1/3, 1/4, 1/2 HP and you need a 1, 2, 4 HP rated one to run/make/cool properly.

the temp you wrote are from the evaporator outlet , you should measure the temp at evaporator base or CPU IHS ,
considering your load @ -25c and cpu temp @ +35c , either you have extremely poor contact or the real base evaporator temp is about 20c . (with a good mount the diff between cpu and evaporator should be about 15c).
In your case i think it is the evaporator fault unable to remove heat fast enough , you need better and bigger evaporator .
but this will lead to another problem the compressor itself is not big enough for such load .
in theory any compressor could cope with load but at the expense of temperature ,
So your compressor could arrange -10-20c @ 200w , while 1/3 or 1/4hp can do [email protected] 200w .

So for max performance almost everything need to be updated , evaporator compressor and condenser (also cap tube optimization and use of better gas such as R507 or at least R404 ) .
But if in budget i would update the evaporator and condenser , this should drop your load temp quite a bit if you size correctly the cap tube (and swap refrigerant ) , near subzero temp load .
then later you could add a better compressor , keep in mind that used compressor can be for real cheap under 50$ ,

I do not know if I need to have it re-gassed, this is normal, you are going to damage the compressor because of xxx.
check compressor temp if under 70c it is ok .
if 80c or higher you need to shorten captube or decrease load on system (reduce your cpu overclock / voltage )

Also please read before getting a compressor , those could be really loud and will ruin all the system due to noise , consider a quite one if you need to go 24/7 , if you are a casual bencher then this should be another story .:D

hope this will help
 
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ShrimpBrime

~MadHatDeLidder~
Joined
Apr 19, 2012
Remove the IHS plate and use a copper plate that's about twice the size and your low temp gradient will improve.