I have an older desktop that feels very slow on Windows 10. I mainly want to use it for email, coursework, and light games such as Civilization III/IV and The Sims. Windows 11's compatibility checker says the processor is unsupported, so I'm wondering whether replacing it would help and what parts would actually fit.
The current specifications are:
- Intel Core i5-6400 at 2.70 GHz
- 8 GB of RAM
- 1 TB Toshiba hard drive
- NVIDIA GeForce GTX 1070 with 8 GB of graphics memory
- 64-bit operating system
The case appears to be an Asus G11CD. I'm looking for inexpensive upgrades rather than a completely new high-end system. What should I buy, and which parts would provide the biggest improvement?
3 Answers
I wouldn’t start by buying an i7-7700K. The 7700K may require a BIOS update and may not be supported by the proprietary motherboard in that Asus system. It also would not necessarily solve Windows 11 compatibility, since that processor is from an older officially unsupported generation. An SSD and more RAM are much better-value upgrades for your current use.
For Civilization III/IV and ordinary coursework, the existing processor and GTX 1070 should be sufficient. First check whether the hard drive is nearly full or failing, then install a SATA SSD and move the operating system to it. If the computer still feels limited afterward, increase the RAM to 16 GB. A new platform would only be worth considering if you specifically need official Windows 11 support or want newer, more demanding games.
Upgrade the memory to 16 GB if possible, ideally as a matched 2 x 8 GB kit. You need desktop DDR4 RAM, but check the exact Asus motherboard or system specifications before buying because speed and capacity support can vary. If the existing 8 GB module is compatible, adding another matching 8 GB stick may work, but a matched kit is generally safer.
They do matter, so don’t buy DDR3 or laptop memory. Confirm the motherboard’s supported DDR4 type and speed, and make sure the system has two usable memory slots.

Thanks—that helps. I wasn’t sure whether the different DDR versions and pin counts mattered.