A Look at the DIY Upgrade to the Processor on a Dell Notebook

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by Kevin Giberson

I recently upgraded my notebook’s CPU, replacing the T2400 Core Duo processor that came installed in the Precision M65 with a T7600 Core 2 Duo. What follows is a general description of the upgrade, which should also apply quite directly to the Dell Latitude D820, a notebook almost identical to the M65, aside for the GPU. The steps and precautions would likely apply to a variety of other reasonably current notebook computers, as well.

That said, there are certain risks involved with a CPU upgrade, and I’m certainly not advocating that anyone do this. I doubt I would have done the upgrade myself had I not been able to find the following: 1) an abundance of helpful information related to notebook CPU replacement and installation, information often generously and graphically provided by members of this site’s forum community; 2) the notebook service manuals that Dell typically makes available; and 3) the exact CPU I wanted for a price considerably below retail.

Anyway, before clicking the Buy It Now button and committing to the purchase of the T7600, I spent a good deal of time asking myself whether or not the CPU swap was worth the cost, the risk or the trouble.


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The Cost

In many cases the cost is prohibitive or simply doesn’t make sense, particularly in view of the prices of brand-new notebook computers.

Though an objective answer to the question of value is impossible, I first considered how much I like the M65. There would be little reason to spend nearly $400 on an upgrade if I were planning to get rid of the machine within a year or so. (The actual cost of the upgrade was $385, including shipping: $365 for the CPU, which I bought from a reputable eBay seller, and $20 to get a replacement heatsink from Dell.) Once I’d decided that I’d probably keep the M65 for at least a couple more years, I looked at what the upgrade would provide and could name two things: improved performance due to higher operating frequency and more Level 2 cache, and 64-bit capability. Of these improvements, the most appealing was the improved performance, but there’s also a chance that 64-bit support will be worthwhile during the time I own the notebook.

One thing I do know is that I would not have made the switch from a T2600 Yonah CPU to the T7600 Merom, nor would I have bothered swapping out a T7200 Merom for a T7600 Merom. These upgrades would probably not offer enough performance gain to justify the cost, at least for me, though the first switch would at least provide 64-bit compatibility.

In the end, the reason I sprang for the T7600 (and the heatsink) was because of two distinct and meaningful improvements, and the fact that I was able to purchase the unused CPU from a trustworthy seller for a good price. I could not have justified paying a whole lot more when the notebook’s current value would not exceed $1,000.

The Two CPUs (with significant differences in bold)

  Old New
Name Yonah T2400 Merom T7600
Number of Cores 2 2
Model T2400 T7600
Frequency 1.83 GHz 2.33 GHz
FSB 667 MHz 667 MHz
L1 Cache 32KB + 32KB 32KB + 32KB
L2 Cache 2MB 4MB
Manufacturing Process 65nm 65nm
64 Bit Support No Yes
Series Core Duo Core 2 Duo
Socket M M

The Risk

I suppose the main risk for me was voiding the nearly two years of warranty coverage that remains on the M65, though I have never bothered to answer a number of questions regarding the warranty. If the LCD fails, for instance, will Dell tell me that it’s no longer covered because I disassembled the notebook, including detaching the LCD from the video connector on the motherboard? I don’t know, and I’m just hoping I don’t have to find out. Another obvious risk was rendering useless a computer upon which I depend. But thanks to all the online help, I wasn’t overly concerned that I would break anything, and my only real worry was increased heat.

The Primary Risk: Heat

I knew from desktop experience that it was very important to correctly install the heatsink, or Processor Thermal-Cooling Assembly, as it’s called in Dell’s service manual. The heatsink sits atop the CPU, the Memory Controller Hub (MHC) and the graphics chip, so its installation is key to avoiding thermal shutdown and destruction. A number of people recommended cleaning and reusing the existing heatsink, applying Arctic Silver thermal compound at the time of reinstallation, and while this probably works well enough (Arctic Silver is certainly an excellent product), I opted to keep everything stock simply because it’s a little simpler to do so, and perhaps a little less likely to void the warranty.

The Trouble – The Actual Upgrade

The upgrade itself was really no trouble at all, thanks to the service manual and the helpful numbering of screws, especially for the heatsink. I did make sure to update the BIOS before I began.

Working slowly and carefully, the disassembly, CPU swap and reassembly took about an hour. There were a total of 28 screws to remove and replace, and I labeled these as I removed them. A number of components had to be disconnected then reconnected during the reassembly: keyboard, wireless antenna, graphics cable, speaker and touchpad.


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Before putting everything back together, I took the opportunity to give the notebook’s interior a little compressed-air cleaning (as illustrated in recent articles on this website) and used high-purity isopropyl alcohol and Q-tips to clean the MHC. The actual CPU swap involved nothing more than loosening the ZIF socket by turning a single screw, popping in the T7600, turning the screw the other way, and installing the new heatsink.


Motherboard base and heatsink. (view large image)

One thing I found interesting was that the old heatsink showed direct contact between the CPU and the heatsink’s thermal pad, and this was also true of the MHC, but the GPU did not appear to have made direct contact with the blue pad installed on the heatsink; this blue material was utterly pristine, leading me to think that the GPU heat dissipation has little to do with the heatsink, at least in the case of the M65 and its NVIDIA Quadro FX 350M CPU.


The old and new heatsinks. (view large image)


A view of the motherboard with the old CPU without the heatsink. (view large image)

First Boot

Everything started up quickly and without any problems, so quickly, in fact, that I missed my chance to go into the BIOS as I’d intended. There was no discernible difference, other than speed, between starting up with the T7600 the first time and the countless startups I’d experienced with the T2400.


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Temperatures

As mentioned, heat was easily my biggest concern. Others’ experience, and to some extent common sense, told me the T7600 would run hotter than the T2400. For stress testing and temperature monitoring, I relied primarily on the software tools in the table below. These programs, which by no means represent a comprehensive list of what’s available and useful, are all easily downloadable and free:

Software Purpose
Prime95 Stress the CPU
Core Temp Display CPU Core Temperatures
EVEREST Home Edition General Hardware Monitoring
ATITool Stress and Monitor the GPU

A temperature comparison (all values are Celsius) revealed the following:

Component Yonah T2400 (Before) Merom T7600 (After)
Core 0 – Idle 45 43
Core 1 – Idle 40 43
Core 0 – Load 67 75
Core 1 – Load 67 75
GPU – Idle 42 53
GPU – Load 75 – 82 73 – 84

So, as far as I could tell, everything was in order. The above temperatures are fairly representative of the before and after picture, and while the core temps of the T7600 are higher under load than those of the T2400, they are in line with what I expected and the data provided by Intel. There has been no instability and no unexpected shutdowns have occurred. Moreover, I can run multiple applications all day long and core temps generally remain in the high 30s to low 40s Celsius, which seems good. GPU temps are essentially the same as before.


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Performance

So what did I get for my $385 and several hours of surfing the Internet to make sure I didn’t screw anything up, along with a couple of hours of actual work? Well, boot time seems significantly reduced, though I unfortunately didn’t measure the “before” time, so the “after” (or current) time of 20 seconds or so doesn’t mean too much. There has been about a 20% increase in performance as measured by PCMark05, and a Super Pi run to two million digits dropped from 1m 21s to 0m 55s, slightly better than a 30% improvement. Overall, things do seem quite a bit zippier (though the 3DMark06 score for the Quadro 350M is still pretty abysmal).

Benchmark Yonah T2400 – Before Merom T7600 – After
PCMark05 3482 PC Marks 4522 PC Marks
3DMark06 691 705
Super Pi 1m 21s 0m 55s

 


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Was it worth it?

It’s early yet, but I have no regrets about the upgrade. I reviewed the M65, purchased from Dell Outlet, for this website a little over a year ago. Although I’ve always been happy with the notebook, the Core 2 Duo Merom was released right around the time of my purchase, and I found myself envying the 64-bit capability and additional L2 cache, and I’d always kind of wanted a faster CPU. At that time, I knew that it would be possible to upgrade from the T2400 to a Merom but was in no hurry to do so. After recently building a midrange desktop computer, however, I began to find the M65 rather slow. This CPU upgrade, including heatsink replacement, was very little trouble and, thanks to a fortunate eBay purchase, was done at a fraction of the cost of a new business-class notebook. So the T2400 to T7600 upgrade made sense for me.

Reasons to Upgrade

  • 64-bit capability

  • Better overall performance

  • Fairly simple to do

  • Can extend the useful life of a favorite notebook

Reasons Not to Upgrade

  • May well void the warranty

  • Minimal performance gain if going from a fast Yonah to a Merom, or a mid-range Merom to a high-end Merom

  • Merom retail prices are high (much higher than comparable Santa Rosa CPUs)

  • This upgrade is from one non-current CPU to another non-current CPU

  • Improper heatsink installation, especially, will cause problems


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