Bulbs keep burning out

So I recently posted about some problems I was having with my LEDs. I fixed the problem by replacing bulbs (using solder).

Everything has been fine ever since (its been a few weeks). However, yesterday I noticed that two bulbs are out (on two different strings).


Here is a basic description:
48 3W Cree xp series LEDs
Two 14"L x 6"W heatsinks - Each have 8 XP-E royal blue, XP-E 8 blue XP-G 4 neutral white, and 4 XP-G cool white LEDs.
80* optics on all.
Runs off 4 dimmable meanwell drivers (12 bulbs/driver) (ELN-60-48P)
RapidLED daylight controller for dimming control and sunrise/sunset control

Here is the original build thread:
http://www.3reef.com/forums/i-made/my-rapidled-build-fts-color-blended-pg6-121438.html

Now my first question is: why do bulbs keep burning out? I did not build this setup myself, I bought it pre-built from atticus818. I was under the impression that LED bulbs were supposed to last 5-10 years.. The system itself is just over a year old, and 4 bulbs (out of 48 ) have burnt out now. Again, these bulbs are not all on the same string.

I am also curious to know why the rest of the string isn't out... These bulbs are wired in series, so shouldn't the rest of the string go out? Like xmas lights?

I really don't want to take this canopy off again and take everything apart... ugh. I am pretty sure I read that I can leave it "as is" without doing any harm if the bulbs are wired in series.

 

What current are they run at?

 

Well I sort of had an incident where I blew up my multimeter. Last I checked:

White runs - 1.25 mA
Blue & white runs - 1.0 mA

This was after the first two bulbs burnt out (each on a different string of lights)

 

Are you running fans on the heatsinks? If not you're likely getting too much heat from the LEDs and they aren't being cooled properly. You should be able to leave your hand on the heatsink for as long as you want, or if you have a temperature gun try to keep the heatsink under about 110 degrees F. Usually we can run 24 LEDs off our 6" x 20" heatsinks but on the 9" version it gets way too hot, so on a 6" x 14" heatsink I'm thinking heat could be a big problem for you.

 

I am actually running an individual fan on each heat sink:
Amazon.com: Noctua NF-S12B FLX 120 mm 3 Speed Setting Beveled Blade Tips Design SSO Bearing Fan SCD 2 - Retail: Computers & Accessories

Also, the back of my canopy is 100% open for air exchange.

 

Are your LED's tapped and screwed into your heatsink or are they glued down?

 

They are glued with this
Arctic Alumina Thermal Adhesive - Rapid LED

 

Hmm was thinking it could be shorting to the screws. No corrosion or anything building up?

 

Very strange.. can you send some pics? As close as possible while still being clear, we'd like to see some of the LED/solder connections