Lapping my XP90.

muddocktormuddocktor
edited May 2005 in Hardware
A few months ago when I built my first NF3-250Gb I ordered a retail XP90 kit (includes a 92 mm fan in kit) from SVC because they were running a special on them and I knew that the XP90 was one of the best hsf's on the market. When I got everything in I assembled the system using a mobile A64 3000+ proc and install the XP90 on it. After booting up and getting everything running at proper speed (mobile A64's initially boot up using a 4 multi and less than 1v vcore) I monitored temps in bios, which were running in the mid to upper 30's. Not bad but certainly not stellar. I installed the os and the DFI monitoring app and also the folding client. While folding at 1800 MHz, the temps were getting up into the low 40's, which I thought kind of excessive for stock speed for a premium hsf. I then installed an 80mm SmartFan2 to see if increased airflow would help but it only improved temps about 1-2 C. The further I increased the overclock on this new system, the higher my folding temps kept going, so I decided to investigate if I was having a contact problem between the hsf and proc core (Mobile A64's have no heatspreader). After pulling the hsf off, the As pattern on the heatsink showed a thickening of material towards the middle of the contact patch. After cleaning the AS off I looked at the heatsink base but could see no obvious reason for this to happen. Then I took a metal straightedge and the problem became clear; the base of the XP90 was concave. :eek::mad:

At that time I also had an extra SLK948-U I had gotten from Gnome several months ago, so instead of working on the XP90 I just installed it and it does a great job cooling that system even at 2700 MHz, with temps in the mid to upper 30's folding. :thumbsup:

Fast forward to the present; I'm building a second NF3-250Gb folding system. I bought another mobile A64 3000+ from Tex and got me another NF3-250Gb board and I plan to use the XP90 I bought earlier but to lap the sucker first, to get it flat first. It took a few hours of steadily lapping as it was pretty concave, but I finally got it flat and had all the nickle plating cleaned of the base too, then cleaned it up and installed it, still using the SmartFan2. After getting this new system up and running, hsf performance was nothing short of phenomenal. At present, I have this new system running at 2430 MHz folding stable and temps are running only 2-3 degrees above the board temp and around the same temps as the pwm temps shown by the monitoring app. :D

Moral of the story: if you bought a premium hsf and temps aren't what you think they should be, check for flatness across the base of the heatsink. It made a world of difference on my XP90 and now I see why people brag on it so much. :thumbsup:

Comments

  • lemonlimelemonlime Canada Member
    edited May 2005
    Great advice mudd. I have a similar problem with my retail barton sink. The copper insert is slightly concave, and it makes a very negative impact on the temps. I get about 60 degrees at load with stock vcore, which is ridiculous. I put an older, smaller, aluminum sink on there with the same fan, and temps went down to low 50s.

    Wish my A64 didn't have a heat spreader on it.. it really does make a big difference in temps without it. I tried to pull it off my old 2800+, but that didn't go so well :D
  • csimoncsimon Acadiana Icrontian
    edited May 2005
    I may need to lap my whitewater. I'm not impressed with it yet. Just meagerly satisfied.
    I've never used the word meagerly before so I hope I used it in context.
    If not ... :banghead:

    ;D
  • muddocktormuddocktor
    edited May 2005
    Have you put a straightedge on it, like a metal ruler (that's what I used to check with), Chris?
  • csimoncsimon Acadiana Icrontian
    edited May 2005
    muddocktor wrote:
    Have you put a straightedge on it, like a metal ruler (that's what I used to check with), Chris?
    not yet.
    I'm probably yanking it this weekend cause my 2 mags came in. I have a metal ruler in the garage so I'll check it when it comes off.
    I looked at it really well before I put it on but sometimes you just can't see that type of thing especially when it has a mirror finish. The whitewaters are all supposedly hand lapped from the mfg or so I thought.
  • Mt_GoatMt_Goat Head Cheezy Knob Pflugerville (north of Austin) Icrontian
    edited May 2005
    muddocktor wrote:
    Have you put a straightedge on it, like a metal ruler (that's what I used to check with), Chris?

    I always put the straight-edge corner to corner in both directions. that is how I was taught years ago in machine shop class.
  • csimoncsimon Acadiana Icrontian
    edited May 2005
    mtgoat wrote:
    I always put the straight-edge corner to corner in both directions. that is how I was taught years ago in machine shop class.
    yeah that makes sense to find perfect center of anything square or rectangular.
    You should try finding the center of a circle or hole sometime! ;D
    Not as hard as you think really. :thumbsup:
  • Mt_GoatMt_Goat Head Cheezy Knob Pflugerville (north of Austin) Icrontian
    edited May 2005
    csimon wrote:
    yeah that makes sense to find perfect center of anything square or rectangular.
    You should try finding the center of a circle or hole sometime! ;D
    Not as hard as you think really. :thumbsup:
    I learned how to do that way back then too. And yes you are absolutely correct on it being easy.;)
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