Potential Video Card upgrades in Studio 540 Mini-Tower

The space inside is small, but there is still enough room for larger dual slot cards if you only have one hard drive and one optical drive.  Basically, what happens with the longer higher-end dual slot cards is that they cover up your top two SATA connectors on your board making them unusable.  Most likely you do not have any PCIe x1 cards below your PCIe x16 slot so you should be OK there also.  My 530 case is very similar to the 540 case and I have a GTS 250 and there is still enough room for the longer GTX 260's and above. 

I don't know how much you want to spend or what games you are going to play or what size monitor you have.  You can still put a lot of cards in your system that would work with your 350W PSU.  Another thing to consider would be heat that is generated by the higher-end cards and the smaller case with limited air flow which is why I would look for a card that exhausts heat out of your case versus keeping it inside.  For example, a GTX 260 216 core will probably run cooler that a 9800GT and exhaust the heat out instead of keeping it inside.   My GTS 250 idles at 41C while my 9600GT in the same case ran at 57C during idle.

Just an update to this thread - I successfully fitted a Radeon 5850 card into the Studio 540 Mini-Tower, along with a Corsair HX 620W Modular PSU, and it all works perfectly. Here's a photo:

As you can see, the new Corsair PSU is at the top of the case, and the Radeon 5850 near the bottom. The 5850 is massive (9.5" in length, plus another half-inch or so for the PCI-Express power connectors which are at the end of the card). The 5850 covers both the SATA1 and SATA2 connectors (which the HDD and DVD-RW are originally plugged into). This can be solved by changing these to SATA3 and SATA4 directly below them. I also purchased new, extra-long SATA cables to connect them (the bright blue cables) which made things a bit easier. The card also blocks up the empty 'HDD1' bay, which means I will be unable to add an additional HDD or optical drive in the future (although I have no plans to anyway).

So, to anybody who is interested, it is possible to install large dual-slot Graphics cards into the trusty Studio 540!! I would definitely advise getting a modular PSU like mine though - as you can see in the photo, I only have cables from the PSU which I need, so the case is not cramped and airflow remains good.

I've upgraded my 540 immensely over the three years I've owned it but only now have I found a graphics card that fits the job. Now, it's worth noting that I upgraded my case to a Coolermaster 690. Well worth doing, if you want to keep the 540 going a while longer. It has far more space, much better airflow and expandability.

Anyway. I'd upgraded my pc to the point that unlike the user above, I needed all the SATA ports (and have even added a pci SATA controller too). So finding a graphics card that didn't cover the two SATA ports. I eventually found the msi cyclone 6850 that, while double slot, does not have a huge case around it and the fan, while large, stops just short of the SATA ports. There's also a nvidia 550ti version, if you prefer their cards.

In comparison to the racket that the previous 9800gt made, this card runs very quiet!