Can I put an i5 3570 (not K) into my i3 2100 socket?

Same socket, but you would need to get a bios update for the board so the 3570 would work which I'm sure the update doesn't exist for a prebuilt computer. My suggestion would be to get an i5 2400 as that will drop right in and work without any sort of hassle.

Same socket. LGA 1155 so that part would "fit".


I don't know what your motherboard is, but you need to check to see if the motherboard supports that processor.

The problem is more the name brand PC's, the bios' are very limited in what they support. If your model of PC had the option of getting the I5 3570 when you bought it, then the MB should support it, as they don't make bio's that or MB's differently for same model lines with different upgrade options, but outside of that, it's hit and miss.

Consdering the i3 is Sandy Bridge and the i5 is Ivy bridge, I'd say the MB probably isn't compatible as Acer wouldn't have offered a Ivy from Sandy upgrade when the unit was selling.

What model # is it exactly, that will help determine what you may be able to do.

Thanks! I think I might actually go for a 3570k instead, any suggestions for a good but cheap motherboard with 2 pcie slots (for sli) and if its possible?, i'd like a mini atx motherboard because my case wont fit a full one and i would rather not upgrade both.

If you are going to grab a new board and want sli in a mini atx form factor, then grab one of these
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
I'm not sure what you consider cheap but that board fits the bill for what you want.

thats a bit too expensive, i'm thinking around 100$

First, we need to know if your motherboard can support an Ivy Bridge CPU, so download CPU-Z and run it to check the make and model of your motherboard, then you / we can check the compatibility list.

Second, if you are running an OEM version of Windows and will be buying a new motherboard, you will have to buy a new key for Windows as well, as it is locked to your old motherboard.

This is what it says:
Manufacturer : Acer
Model : Aspire M3920
Chipset : intel, sandybridge, Rev. : 09
Southbridge : Intel, H67, Rev. :B3
LPCIO : ITE, IT8728
Bios:
Brand : american megatrends inc.
Version : P01-A3
Date : 12/18/2011
Graphics interface:
Version : PCI-Express
Link width : x16, Max supported : x16
I dont really know what all this means  
But if I got a new motherboard would i need to reinstall windows?  

Yes, OEM stands for Original Equipment Manufacturer, and in this context what it means is that Microsoft sells cheaper (wholesale) copies of Windows so that system resellers (like Dell, HP, Acer, etc, but also much smaller operations) can package the operating system with their products. But each OS install is meant to go with a single computer system. We consumers can also buy OEM copies of Windows; the downside is that once you've registered the access key, you're stuck with one motherboard.

Retail copies of the OS are far more expensive, but they allow you to transfer the install to different systems.

Anyway, that bit of rambling out of the way, gorz, danny2000, and getochkn have it right: an i5 3570 (Ivy Bridge) will physically fit in your motherboard socket, but because the i5 3570 is a current-generation product, your last-generation motherboard won't recognize it by default. Ordinarily, that wouldn't be a huge problem; you could update the motherboard's BIOS to allow it to recognize the newer processor -- but since you're using a pre-built Acer, you probably shouldn't even attempt to update your BIOS.

So the upshot of all of this is that your best bet is to use a last-generation i5 (Sandy Bridge), like this one: Core i5 2400. Or this one: Core i5 2500. Any Core processor whose model number starts with a 2 ought to do (just like your current processor, the Core i3 2100). The 2 stands for second generation. The 3570 is obviously a third generation Core product.

Happily, there isn't a whole lot of practical difference between the two processors. The second-gen, Sandy Bridge i5 is plenty fast.