Question Upgrading a Dell Inspiron 3000 i3847-3850BK


Sep 12, 2010
We bought our son a used Dell 3000 i3847-3850BK desktop recently. He's a college student in Intelligent Systems Engineering and wanted a desktop to fiddle with. He loves gaming too. It comes with a 4th generation Haswell 3.5 GHz Intel Core i3-4150 processor. According to all I can fine, it can be upgraded to a Intel Quad Core i7 (4th Generation) and I think the model it would take is an Intel Core i7-4790K Processor (8M Cache, up to 4.40 GHz) BX80646I74790K. Could you let me know the following?

  1. If you know, is it correct that we can do this upgrade?
  2. Seems like there are used ones available for $85 (used, from China) to $255 at Amazon (new, boxed, BX80646I74790K). Is it safe to get a used one?
  3. If we get one should we also get thermal paste? I used to build PC's in the past and assume this is still needed. Any recommended type(s)?
  4. Should we get a new fan? In the past I always replace fans with processor upgrades, but not sure if that's a need. Current fan in working on the i3.
  5. Will there be a performance boost? The machine has 8gb of memory and we were going to upgrade it to 16gb. Do you think the memory will provide any boost?

Let me know on the above and thank you!



1. Upgrading to the I7-4790K is possible as other users have reported it working:

NOTE: before upgrading make sure you're updated to the latest BIOS.

2. $255 is too much... I wouldn't pay over $120-130 for that CPU. If you could find it used cheaper I'd go for it... CPUs do rarely fail. I'd feel safer if you could actually test the CPU before buying, finding someone locally would be better as opposed to China(though if you're buying from aliexpress you can actually get your money back through a dispute if the product is not working).

3. Yes, definitely, thermal paste is needed... you can find something like Arctic MX4 really cheap. Make sure you have some isopropyl alcohool on hand to clean up the cooler, the old CPU and the new one (even if it's clean it's always a good idea to do it one more time before applying new thermal paste). As for the application method, a rice grain or a vertical line down the center of the heatspreader should be fine.

4. I'd check the temps first with the old cooler... if it's getting too hot during workloads (85C+) you should change it.

5. Depends on what your son's doing. More recent games might require more RAM(you'll usually get some stuttering when it's not enough), but again you'll need to test it out first. Also, adding another module(even if it's the same model) might result in stability issues or your system not even POSTing, but it might work without problems aswell. When buying the module I'd make sure that you can actually return the stick in the case of compatibility issues with the old one.

EDIT: if a moderator comes by... this should be moved back to SYSTEMS, he has the desktop Inspiron 3847.
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