Choosing a 660p PCI-E card involves some trade-offs.
Choosing a 660p PCI-E card involves some trade-offs.
I was installing a Dell Inspiron 660p upgrade and couldn't boot with the full graphics card (HD5870). Fortunately, the CPU came with built-in graphics thanks to the i5 3330. I updated the BIOS to the latest version (A13) but still faced issues. I tried different power supplies: a 500W rosewill and a 650W cooler. I also swapped out the graphics card—used GTX 310, HD5870, HD7950, and GT710. All these worked on my little Tesbench. Notably, the GT710 isn’t a full PCIe 16 slot and functioned (it’s more like PCIe X8). The others were full PCIe 16 cards. I connected external PCIe connectors as well. I’m not very familiar with OEM BIOSes, so there might be something missing, but hopefully the board is fine. Full specs: Dell Inspiron 660 OEM motherboard, Intel i5 3330, St3500630ns, 500GB SSD, VAPOR Radeon HD 5870 Rosewill RD500-2DB, 500W PSU, Micron 1600MHz 2x4GB DDR3.
The i5-3330 supports only 16 PCIe lanes. The HDD will require either 2 or 4 lanes, and the WiFi module (if installed) will need 2 or 4. Is there a BIOS setting to change the x16 slot to x8? Alternatively, you could disconnect the HDD and remove the WiFi module to test if booting into BIOS with more lanes for the GPU is possible.
The person making the argument is incorrect... the HDD won't use 2 or 4, nor will the Wi-Fi module. That's unrealistic. The CPU has its own PCIe lanes, and the chipset generates its own PCIe lanes with a dedicated link to the CPU. The SATA controller is integrated into the chipset and doesn't rely on those PCIe lanes made by the CPU. The wireless card is likely to use a single PCIe lane provided by the chipset. The PCIe slot can accommodate up to 16 lanes, but this isn't mandatory—the actual lanes inside may vary (for example, an X16 slot might have only 4 or 8 lanes). Video cards and PCIe devices are built to operate with as few lanes as possible and adapt to different configurations. In theory, a video card could function in an x1, x4, x8, or x16 slot. The device shouldn't need to know the exact count.
There are some exceptions, though. Typically, SCSI controllers or high-end network cards might struggle if the slot only has one lane, since that limits speed to around 950 MB/s and two 10G ports require at least 2.5 GB/s. In your situation, it seems like a Dell BIOS quirk or a lack of UEFI support in the motherboard could be the issue. I'm certain some AMD cards had UEFI firmware on them (like bios on the video card), which would prevent initialization if the BIOS lacks UEFI features. With older motherboards that have basic BIOS without UEFI, such cards probably won't work.
RX 4xx and newer from AMD use UEFI firmware, while RTX 2xxx and newer from nVidia also support it. Earlier models should generally function even on older systems. A few rare video cards have customized firmware that's locked to specific platforms—HP was known for this.