Lapped Phenom II X4 955, Earned 2c

Hi. Just joined the boards here. I got into AMD CPU's and overclocking back with the Thunderbird chip. I went from a P3 900 to an Athlon Tbird 1.2ghz proc back in the day. From there I got into overclocking a little bit...although I only got that chip to 1.4ghz heh.

Anyways, I just built a new computer around the Phenom II 955, and I guess what is called the spider platform. Running the CPU on an MSI 790FX mobo with a Radeon 4890.

I have the V8 heatsink from cooler master and in preparation for overclocking I've been working on airflow and thermal transfer with the CPU and heatsink. The other day I was running at 50c full load but it must have been really hot in my room because today I was at 46c, 25c ambient temp in my room.

Anyways I had been reading a bit about lapping and decided to give it a go. The heatsink actually had a very good finish to it so I didn't bother with it. Intead I turned to the CPU and began lapping it. Below are my results. I've seen better, but I didn't want to revert to polish in case the chemical penetrated the copper, hurting any gains I would have recieved.

I took a pic before of course, so I had the stepping info


Now I'm at between 43.5 and 44c full load. I'm hoping to gain a bit more as the TIM sets over the next few days and cycles. Overall thats roughly 2-2.5c. I've very happy with how it turned out and at those full load temps I feel like I can begin tweaking and seeing what I can get this puppy to on air. I've read many reviews about the V8 handleing increased voltage and heat very well.

Idles 32c

Not bad, but I noticed you mentioned the heatsink having a nice "finish." Really the finish of it has nothing to do with it. There was a thread that I can't remember (will look for it) but it showed a flat lapped cpu that wasn't shiney compared to a shiney lapped cpu that wasn't flat.

Edit: Found it!

ChanceCoats123 said:

Not bad, but I noticed you mentioned the heatsink having a nice "finish." Really the finish of it has nothing to do with it. There was a thread that I can't remember (will look for it) but it showed a flat lapped cpu that wasn't shiney compared to a shiney lapped cpu that wasn't flat.

Edit: Found it!

Click to expand...

Next time I have it off I'll have to check it for flatness but it looks like it was machined by an end mill operation and that is usually pretty flat. +/- .001-.003 not uncommon. Not sure if thats flat enough but yeah, haha.

I did single directional lapping on the CPU. Checked for flatness with a razor. No light although it seemed like the thickness of the shell was not consistent because the copper showed earlier on the outsides and a spot in the middle before filling out the entire chip. **Shrug**

yea they are like that, some of the older chips will have a high side along one whole edge kind of a pain.
also about the shiny finish, you can get super shiny and still be flat but theres really not mush point, thermal grease/compounds are arround for a reason.

there was also some place that compares super shiny vs finely sanded and dull and dull seemed to have a bit more improvment for some reason.
i cant remember why but i think it was something to do with the channels made in the surface of the material (tiny tiny channels) are better at dissapating the heat than a absoutly flat surface.