One COB running hotter

Kul

Kul

Active Member
4 x CXB3590 running at 50W with reflectors on passive pin heat sinks 150mm 60-70w
First COB in series running hotter then the rest.
COB1 - 108F at top of heat sink
Remaining 3 avg. 101F

Is this normal?

Even at 101F temps seem high, should i be concerned?
 
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110f is fine.does the hot cob have the same air movement the other 4 are getting? im thinking maybe theres a dead spot there ?
 
Any lumen benefit to running them cooler? Also im running at 200w from wall could push it to 236w but already at 108F. Not to pleased with these pin heat sinks.
 
Shugglet said:
cooler cobs put off more light.

If I had to guess I'd think it would be TIM application differences perhaps.
Click to expand...

Haha had to look that one up. Yup that was my first thought. Need to double check it but I'm fairly consistent with my thermal paste applications.

I'm using Noctua thermal paste
 
Kul said:
Haha had to look that one up. Yup that was my first thought. Need to double check it but I'm fairly consistent with my thermal paste applications.

I'm using Noctua thermal paste
Click to expand...
it is strange.i have 75w cobs on a 140mm sink and temps are steady at 105f all day even the one in the corner getting the least air flow is under 110f.maybe the paste is the problem?
 
sixstring2112 said:
it is strange.i have 75w cobs on a 140mm sink and temps are steady at 105f all day even the one in the corner getting the least air flow is under 110f.maybe the paste is the problem?
Click to expand...

So just turned it up to 236W and 2 are reading 110F 2 are reading 106F.
Im measuring directly above the cob on the top of the heat sink.
 
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