So WingZero30 are you going to belt sand it flat or hand lap all the way?
I used hand lap and kitchen countertop for lapping as I didn't have glass
.
The grit of wet and dry sand papers I used were as follows:
Q6600:
120, 180, 240, 320, 400, 600, 800, 1000, 1500, 2000 grit
IFX-14:
120, 180, 240, 320, 400, 600, 800, 1000, 1200, 1500, 2000 grit
BEFORE LAPPING
Q6600
IFX-14
DURING LAPPING
Q6600
IFX-14
AFTER LAPPING
Q6600
IFX-14 (Although this isn't my IFX-14 picture as I forgot to take the pic after lapping but the result is similar to what is shown in the photo)
First Lapping session duration
Q6600
3.5 hours
IFX-14
1.5 hours
Contact Pattern after 1st lapping session
Second Lapping session duration (120 grit paper)
Q6600
1 hour
IFX-14
3.5 hours
Third Lapping session duration (120 grit paper)
IFX-14
1 hour
Contact pattern after 3rd lapping session
As this was my first lapping experience, one thing I learnt was that lapping requires lots of patience and time. After all we are shaving surface of metal especially considering this was hand lap.
I started with using 400 grit paper and wetting it slightly with water that was filled with some dishwashing liquid. I used Q6600 first for lapping and used the black protection cover for CPU backside,as seen in the photos above.
In terms of lapping method I held the Q6600 by the edges and letting the weight of CPU do the work and used about 20-30 passes of back and forth. Then rotated the CPU 90 degree and repeated the same movements and so on.
However during lapping, I checked the backside of Q6600 and saw slight water on some of the lga 775 contact points!!
. I then stopped lapping, dried the Q6600 backside and rushed back to my PC case and motherboard to check if Q6600 was working perfectly fine. It was!! phew
Afterwards I didn't bother with wetting sand papers in the case of Q6600 and just used dry surfaces of sand papers.
While using 400 grit paper, I noticed I wasn't making much progress, so moved to 320 grit and then 240 grit. The latter two sandpapers were mostly used to do most of the work of removing nickel plating from Q6600 IHS. However they left scratches which were mostly removed by making use of rest of sand papers starting with 600 grit and finishing with 2000 grit leaving a nice shiny mirror like copper IHS of Q6600.
From the pic of Q6600 during lapping, it can be seen that IHS isn't flat either but rather convex at the centre and edges. However when starting lapping Q6600, the edges of IHS were the first one to show copper indicating that the Q6600 IHS is concave at the beginning. This is also further supported by my unlapped IFX-14/Q6600 contact pattern where greatest pressure was exerted at the edges.
In the case of lapping IFX-14, I started with 240 grit, moving to 180 grit and then finally to 120 grit as these three sandpapers I used generally did most of the lapping work.
These sand papers were wetted initially and I placed my hand on the top surface of IFX-14 base, applied light pressure and letting the weight of heatsink do most of the work. After about 30-40 passes of back and forth motion, I swapped sides and repeated the procedure. Then heatsink was rotated 90 degree and again repeating the same procedure of 30 passes of back and forth.
The back and forth method is more or less similar to what the guy does with his IFX-14 in this video starting at 05:15 :
IFX-14 is a nightmare on dry lower grit sand papers
and requires slightly more pressure to move. However I have found dry surfaces to be more effective than wet surfaces in the case of both IFX-14 and Q6600.
The pic of IFX-14 during lapping complements the unlapped IFX-14/Q6600
I shaped pattern.
Here's the interesting part:
After 1st lapping session, the nickel plating was gone from both Q6600 IHS and IFX-14 base. Total time had already been 5 hours by then and I though that they would be both flats. How wrong was I. I did the pressure and contact and to my dismay the results weren't very encouraging
.
It seems even after 5 hours of hard work of lapping, there was still poor contact area. I have read many times on other forums that people saying lapping didn't improve their temperature results. I suspect they probably got more or less same result as me or that their heatsink/cpu sufaces were very flat already. So it shows that just having copper surfaces on both CPU IHS and Heatsink base after 'lapping' doesn't mean they are perfectly flat.
Any way two days later I carried out my second lapping session and this time only using 120 grit paper to work on both CPU and Heatsink. After the second session, I could feel the difference. Before lapping, IFX-14 used to wobble a lot sideways. However after second session that wobbliness reduced significantly.
On the following day I spent another hour lapping IFX-14 with 120 grit paper and by this time I have accumulated
over 10 hours of total lapping time!! and was becoming tired and bored
. Afterwards I did another contact and pressure test. Although I wasn't expecting perfect flat/contact area, the result showed an increased contact area as seen in the 2nd pic
. The pressure has decreased slightly overall compared to first picture aswell as unlapped contact pattern.
When it comes to lapping, IFX-14 base is very stubburn and even after 6 hours of lapping IFX-14, it still wasn't perfectly flat. Plus the flashlight/torch showed still very small amount of light seeping through either side of central contact area between IFX-14 and Q6600.
CPU IHS seemed more flat with similar light test in that only very tiny amount of light could be seen near the edges while no light was going through the centre and beyond.
I think IFX-14 will still require few more hours of lapping before it can be perfectly flat. One thing I did notice when projecting light through was that there were tiny grains/particles/high spots residing between IFX-14 and Q6600 especially in those areas where light was still penetrating through. It seemed as though these particles were preventing the absolute contact between Q6600 and IFX-14.
I don't know if they are metallic particles/spots or just grit particles which have become attached to both IFX-14 base and Q6600 IHS. I used isopropyl alcohol in between changing sand papers for cleaning.
Those particles resemble the 2nd diagram in the following pic:
irregular contour on both sink & IHS and as few people lap to correct the problem (5%?)and fewer lap to perfection we add another .05 ml for a total of 0.1ml.
Another factor associated with irregular contours is another mil or two layer of compound is added on the high spots depending on the pressure applied. To fill that gap we add another .05 ml for a total recommended amount of 1.5 ml which approx. equals our 5-5.5mm size bead on center. or 3-4 applications with a 7 carat/0.5ml tube
Thermal compound is a volume application to fill gaps, not one of weight, liquid spread-ability etc. and our view that whatever the compound you still need the equivalent volume to close that gap.
Afterwards I installed everything back in my PC case. However in doing so I managed to warp/bend my motherboard and this affected the ram slots. Luckily I managed to sort out problem.
http://forums.overclockers.co.uk/showthread.php?t=18273358
As much as I wanted to do proper lapped testing with all three thermal compounds which I used previously, sadly I won't be proceeding with lapped testing for fear of bending my motherboard again.
However on the bright side here is the IC Diamond results for [email protected] before and after lapping:
Since testing previously I have overclocked my Q6600 further to 3.5Ghz. So some of the bios settings have changed from older settings but they remain same at 3.5Ghz. My unlapped testing was done about 3.5 weeks ago during afternoon.
[email protected]
Bios Vcore: 1.40V
Idle Voltage: 1.376 - 1.360V
Load Voltage: 1.360V
Load Line Calibration (LLC): Enabled
Ram Speed: 518.7MHz (DDR2 1037MHz)
Ram timings: 5,5,5,15
Dram Voltage: 2.00V
EIST and C1E: Disabled
Ambient room temperature: 20.0C (in both tests)
IC Diamond Before Lapping
Results taken from here:
http://forums.overclockers.co.uk/showpost.php?p=18930615&postcount=2287
IC Diamond After Lapping
The lapped testing took almost 4 hours with 120 passes of Intel Burn Test starting at 12.06 pm and finishing at 15.50pm. So took the whole afternoon when the day is at it's warmest temperatures.
Lapping although still not perfect has produced several astonishing results:
1) Temperature reduced by 6C for hottest cores
2) Temperature reduced by 3C for coolest cores
3) Temperature difference between hottest cores (core0,1) and coolest cores (core2,3) reduced by 3C
4) Average temperature reduced by 4.5C!!
I am impressed
I think for perfectly smooth and flat contact between Q6600 and IFX-14, average temperature could further reduce by 2-3C more. IFX-14 is an impressive cooler but only after lapping it.But as things stand I am very happy.
In my concluding thoughts the ideal case of temperature reduction and for thermal compound maximum performance is high pressure and large contact area.
However in my specific case, it wasn't the pressure but rather the increased contact area that astonishngly reduced my core temperatures.
I think there is definitely a tradeoff/balance between pressure and contact area and having high pressure doesn't always equate to higher performance although it is essential. The contact area is just as important as pressure.
What a journey it has been.
From learning about IC thermal compounds to asking questions/participating in IC threads to carrying out testing to further refining variables and finally today, it has been a brilliant knowledge gaining and understanding mission about how thermal compounds as part of PC systems work and why they behave the way they do.
WingZero30