|Your mboard is:|
"PJ467-69001 Motherboard (system board) - Puffer, UL8E"
Nothing in this about the PCI-E version:
HP and Compaq Desktop PCs - Motherboard Specifications, PTGD1-LA (Puffer)
Motherboard description Motherboard: ASUS PTGD1-LA
HP/Compaq name: Puffer-UL8E
I found the OEM manual for it, but I searched it and found nothing in this about the PCI-E version:
Since that's the Asus manual, it's likely the PCI-E is 1.0 if the version is not stated, but I don't know for sure.
You could look here in the specs or manuals for other Asus socket 775 mboards that have the 915P chipset:
Asus mboards by chipset and socket type:
I'm assuming that lists older models as well as current ones.
Specifications links not working at present (maintenance).
You could search for the downloads for a model to find the manual, or search for specifications for a model on the web.
Most likely to be similar to yours:
P5GD1, VM, Pro
ASUS P5GD1 ATX LGA775 915P DDR PCI-E16 2PCI-E 3PCI SATA RAID Sound GBLAN Motherboard
Less likely - PrGD2, Deluxe, Premium
P5GDC Deluxe, Pro
You could try searching on the AMD site (ATI merged with AMD a few years ago) to see whether a PCI-E 2.0 spec video card can or cannot work with PCI-E 1.0 spec mboards - if you can find that, they would know.
Or you could e-mail them.
Your original power supply is:
"5187-6114 Power supply - 300 watt (Merlot B, Regular)"
The Radeon 4650 PCI-E X16 chipset requires:
"450 Watt or greater power supply with 75 Watt 6-pin PCI Express® power connector recommended"
(FYI - I recommend the Sapphire 4850 - same min power requirement, much better chipset, it's fan is superior - cools better, less noise.)
Your power supply must have at least the minimum capacity required to support a system with the graphics card you are using installed, or the max graphics card you might install in the future.
(Onboard video - video built into the mboard - IS NOT A CARD!)
You can go to the video card maker's web site and look up the specs for the model - often under system requirements - the minimum PS wattage, and, more important, the minimum amperage the PS must supply at 12v is stated. If you don't find that, any card with the same video chipset including any letters after the model number has very similar minimum PS requirements.
Some power supplies have more than one +12v amperage rating - they have two - in that case you add the rated max amperages to determine the total +12v amperage rating.
If you need to replace the PS, you can usually replace it with any decent standard sized standard ATX PS.
Standard (PS/2) power supply size - 86mm high, 150mm wide, 140mm deep, or 3 3/8" h x 5 7/8" w x 5 1/2" d , or very close to that, though the depth can be more or less for some PSs.
Don't buy an el-cheapo PS.
See response 3 in this:
I believe part of what the PCI-E 2.0 version requires is that the mboard be able to support the current (amperage) requirements of the card you install., and that requirement is higher than for version 1.0 and 1.1.
If you choose a card that requires a lower minimum PS capacity, it's more likely you'll have no problems with it working properly with the mboard.