Trouble with Yamaha 2200E

[bizaree]

I've bought Yamaha 2200E OEM.

And i use the latest nero 5.5.2.4.

But when i burn at 20x or 16x, the nero always down the speed to 8x(It said down the speed due to the media).

But it must be wrong, because i use Verbatim 16x original which is recommended to be writed at 20x (www.cdrwcentral.com).

So i try to disable the optimum write speed control, and the buffer under run protection, but the result is stil the same.

I try it to the other computer, and the result is same.............

My computer specification :
A:
Intel Celeron 266 Mhz
Jetway Motherboard 911An (VIA Chipset)
64MB Ram
Quantum Fire Ball 4.3GB
4MB S3 Trio 3D

B:
Abit BE6-II
Intel Celeron II 566Mhz (overclock to 850)
256MB RAM
20GB Quantum Fireball Lct
GeFOrce II MX Winfast
Pioneer 16x DVD-ROM
SB Live Value


I bought this 20x CD-RW at 220US$ is useless, because it's only can write at 8x.....

Anybody can help me, what's wrong, is it my computer, or Yamaha CD-RW has bad product ??????