PCI vs PCI-E?

[Starboy Fantastic]

Hello there,

I recently purchased a mid-range gaming pc:
AMD Athlon 64 x2 core 4200+
2 GB DDR 400
160 GB SATA / 500 GB Seagate

Here's the sitch:
I ran 6.1 to test out the computer with a
PNY GeForce FX 5200 256MB DDR PCI card. The 3d (and some 2d) tests were horrible. I was getting around 150 for simple 3d, 30 for medium, and 6.8 for complex. Switching to 16 bit color improved the simple 3d slightly

So I dropped in a PCI-E x16 WinFast PX6200 128MB. The difference was amazing. In 16 bit: simple 3d jumped to simple: 489 FPS, medium: 76.9, and Complex 26.1. Switching back to 32 bit dropped these umbers, but still demolished the PNY PCI card.

Now I understand PCI-E is favored over PCI for video interface, but I cannot imagine selling a 256MB GeForce video card that gets less than 7FPS at 800x600x32 is gonna push many units. The question is: am I missing something exclusive to the PCI card, or is it just bottlenecked? Why does the 128MB PCI-E run circles around the PCI 256MB?

Regards,

[David (PassMark)]

PCI is a shared low bandwidth parallel bus. 66-MHz PCI gives 266 MB/sec for 32bit transfers. Further all of the available bandwidth of the PCI bus is limited to one direction (send or receive) at a time. Finally the PCI is often connected to the CPU via the southbridge chipset. So the path from the CPU to the video card is,
CPU <--> Northbridge <--> Southbridge <---> PCI Bus <---> Video card
Which is inefficient.

PCI-Express is a point to point (not shared) high bandwidth bus. PCI-Ex16 gives about 8 GB/sec. It also also closer to the CPU.
CPU <--> Northbridge <--> PCI-E Bus <---> Video card

So it is 32 times faster, bi-directional, isn't effected by other PCI devices and has lower latency.

In short you would be nuts to use a PCI video card unless you system is so old that it doesn't support AGP or PCI-E