This is not meant to be a tutorial, but I did want to briefly share my experiences. My quest was to make my Alpha P7125 heatsink as efficient as possible. So, I decided to lap the Athlon core and attach the core directly to the back of my Alpha. I now have the piece of mind, that my temperature reading is as accurate as possible (using a probe), and my Athlon/Alpha combo is performing as best it can. Here are my preliminary temps using VIA hardware monitor v2.03:
With case sides off: Room:25C/78F, System:24C/75F, CPU:34C/93F
With case sides on: Room:25C/78F, System:35C/77F, CPU:36C/96F
These temps are taken after the computer has been running for 5 hours and performing relatively simple operations. I will update my finding after running more demanding applications.
UPDATE: After some running some demanding graphics applications and games, the CPU temp rose to 100F.
My old CPU temp.using an unmodified Athlon 850 and the Alpha was 90F with the case on. The temp. probe was on the finned side of the heatsink, along the bottom.
Athlon 850 (not overclocked)
KA7-100 mobo
Alpha P7125 heatsink w/dual fans
Arctic Silver thermal compound
slot fan (cyclone, blower, exhaust)
MODIFYING THE ALPHA: I decased the Athlon and removed the 4 posts from the Athlon heatplate (the 4 posts that the spring clips attach to). I drilled the back of my Alpha, and pressed in the 4 posts I just spoke of. I also used the original spring clips to hold the Athlon cpu PCB directly to the Alpha
PLACING THE TEMP. PROBE: I taped the temperature probe to the backside of the Alpha, prior to affixing the the Athlon cpu PCB to the Alpha. However, I knew exactly where the Athlon core was going to make contact with the Alpha, so I taped the probe to lay as close to the core as possible. I even cut away the tape so I could place the probe within .5mm.-1mm. of the core's edge. I located the probe below (the side that parralles, and is closest to the Slot A connector) the Athlon core. This was to insure that the probe didn't get cooled by the slot fan blowing over it. Even though the tape covers the probe, the air from the fan could cool the tape, which in turn would give a less accurate temperature reading.
LAPPING THE CORE: I started lapping the Athlon core with 1000 grit paper. I then finished it off with 1200 grit. I didn't feel it was necessary to get it smoother so I stopped with the 1200 grit. I don't recommend lapping an Athlon. There are many articles about lapping Celerons, but the large surface area of the Celeron makes it very easy for anyone to create a flat smooth surface. The .18 mi. Athlon core is so small, it is very difficult to have enough control to create a flatter surface than the original surface. Yes, you can get the surface much smoother by lapping, which is why I did it, but chances are, most people will make the core worse in terms of flatness. Flat is more important than smooth.
COOLING THE CACHE: Initially I thought that AMD made a huge blunder by not allowing the Cache to make solid contact with the heatplate. And to make things worse, they made depressions in the heatplate so a heatsink wouldn't make contact in that area. I also was baffled why the stock heatsink wasn't flat across the entire length. Someone enlightened me that the temperature of the heatsink, might be greater than the Cache could get. If that is true, that means heat would flow from the heatsink into the Cache, making it hotter. It now made sense to me why AMD designed it the way they did. The method I devised to cool the Cache better, was to mount a slot fan directly above the Athlon cpu PCB, and have it blow straight down towards the Slot A connector. This had the added benefit concentrating the air flow into the space between the Athlon cpu PCB and the back of the Alpha, and also cooling the other side of the Athlon cpu PCB. I positioned the slot fan about 1mm.-2mm. from the top of the Athlon cpu PCB. I affixed the fan to the side of the dual fans on the Alpha using double stick tape (for mirrors). This tape is very strong, the fan is very secure. I sawed off the protruding metal ends (part the gets screwed into the PCI slot) of the fan, so I could position it very close to the top edge of the Athlon. I also had to saw off 3/16" off the end of the slot fan in order to be able to put the case side back on.
Alpha heatsinks are extremely heavy. I modified the existing plastic support pieces that support the end of a stock Athlon heatsink. It is way too complicated to explain (involves cutting, heating, and fiberglass), but my Alpha is solidly affixed to the motherboard.........no wobbling.
A "Thank You" must go out to Nevin at the CoolingStore for expediting my purchase of the Arctic Silver grease.
PS: I am not very computer literate, however I am very mechanical. So, most of my education for these modifications comes from visiting websites, newsgroups, and lots of common sense.
Marc
With case sides off: Room:25C/78F, System:24C/75F, CPU:34C/93F
With case sides on: Room:25C/78F, System:35C/77F, CPU:36C/96F
These temps are taken after the computer has been running for 5 hours and performing relatively simple operations. I will update my finding after running more demanding applications.
UPDATE: After some running some demanding graphics applications and games, the CPU temp rose to 100F.
My old CPU temp.using an unmodified Athlon 850 and the Alpha was 90F with the case on. The temp. probe was on the finned side of the heatsink, along the bottom.
Athlon 850 (not overclocked)
KA7-100 mobo
Alpha P7125 heatsink w/dual fans
Arctic Silver thermal compound
slot fan (cyclone, blower, exhaust)
MODIFYING THE ALPHA: I decased the Athlon and removed the 4 posts from the Athlon heatplate (the 4 posts that the spring clips attach to). I drilled the back of my Alpha, and pressed in the 4 posts I just spoke of. I also used the original spring clips to hold the Athlon cpu PCB directly to the Alpha
PLACING THE TEMP. PROBE: I taped the temperature probe to the backside of the Alpha, prior to affixing the the Athlon cpu PCB to the Alpha. However, I knew exactly where the Athlon core was going to make contact with the Alpha, so I taped the probe to lay as close to the core as possible. I even cut away the tape so I could place the probe within .5mm.-1mm. of the core's edge. I located the probe below (the side that parralles, and is closest to the Slot A connector) the Athlon core. This was to insure that the probe didn't get cooled by the slot fan blowing over it. Even though the tape covers the probe, the air from the fan could cool the tape, which in turn would give a less accurate temperature reading.
LAPPING THE CORE: I started lapping the Athlon core with 1000 grit paper. I then finished it off with 1200 grit. I didn't feel it was necessary to get it smoother so I stopped with the 1200 grit. I don't recommend lapping an Athlon. There are many articles about lapping Celerons, but the large surface area of the Celeron makes it very easy for anyone to create a flat smooth surface. The .18 mi. Athlon core is so small, it is very difficult to have enough control to create a flatter surface than the original surface. Yes, you can get the surface much smoother by lapping, which is why I did it, but chances are, most people will make the core worse in terms of flatness. Flat is more important than smooth.
COOLING THE CACHE: Initially I thought that AMD made a huge blunder by not allowing the Cache to make solid contact with the heatplate. And to make things worse, they made depressions in the heatplate so a heatsink wouldn't make contact in that area. I also was baffled why the stock heatsink wasn't flat across the entire length. Someone enlightened me that the temperature of the heatsink, might be greater than the Cache could get. If that is true, that means heat would flow from the heatsink into the Cache, making it hotter. It now made sense to me why AMD designed it the way they did. The method I devised to cool the Cache better, was to mount a slot fan directly above the Athlon cpu PCB, and have it blow straight down towards the Slot A connector. This had the added benefit concentrating the air flow into the space between the Athlon cpu PCB and the back of the Alpha, and also cooling the other side of the Athlon cpu PCB. I positioned the slot fan about 1mm.-2mm. from the top of the Athlon cpu PCB. I affixed the fan to the side of the dual fans on the Alpha using double stick tape (for mirrors). This tape is very strong, the fan is very secure. I sawed off the protruding metal ends (part the gets screwed into the PCI slot) of the fan, so I could position it very close to the top edge of the Athlon. I also had to saw off 3/16" off the end of the slot fan in order to be able to put the case side back on.
Alpha heatsinks are extremely heavy. I modified the existing plastic support pieces that support the end of a stock Athlon heatsink. It is way too complicated to explain (involves cutting, heating, and fiberglass), but my Alpha is solidly affixed to the motherboard.........no wobbling.
A "Thank You" must go out to Nevin at the CoolingStore for expediting my purchase of the Arctic Silver grease.
PS: I am not very computer literate, however I am very mechanical. So, most of my education for these modifications comes from visiting websites, newsgroups, and lots of common sense.
Marc
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