Deskpro EN Pentium II 450Mhz. 80 pin cable required?

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Lilla - 28 Nov 2004 00:50 GMT

I am upgrading the COMPAQ Deskpro EN Model 6450+ (details below) for my
nephew.

I am adding a 8GB ATA/66 (to run at ATA/33 on this computer) drive; this
plus the 6.4GB ATA/33 stock drive will be enough to run Windows XP.

The manual (see link and quote from manual below) says two hard drives on
one cable

requires a 80-pin cable in order for both drives to run at 33MB/s.

It says a 40-pin cable with two drives attaches will limit drive speeds to
25MB/s.

Is this true?

And if it is true, is this true for other computers as well and I just
didn't realize it?

I have a 40-pin cable with double connectors I had planned to use, but if
this limits drives to 25MB/s I will get an 80-pin cable.

Please advise.

Thank you,

Lilla

--------------------------------------------------------------------------------------------------

The computer I am upgrading is:

Compaq Deskpro EN. Model 6450+ (oddity: the model is shown as 0400h by CPUz,
Everest)

Minitower

Pentium II, 450Mhz (Slot 1)

Chipset 440BX

6.4GB HDD

HDD Controller is ATA-33 (aka ULTRA-33)

Intel PRO/100+ NIC (PCI Card)

ATI 3D RAGE PRO AGP 2X 8MB

ROMPaq for Deskpro EN Series (686T3 ROM) 99_08_22, latest available,
installed

3 Memory Slots: 168-pin 100MHz SDRAM unbufferred. 128MB (2 x 64MB)
installed.

--------------------------------------------------------------------------------------------------

http://h200007.www2.hp.com/bc/docs/support/UCR/SupportManual/TPM_dsk-113e-0498/T
PM_dsk-113e-0498.pdf

Technical Reference Guide (Apr2000)

For Compaq Deskpro EN Series of Personal Computers / Desktop and Minitower
Form Factors

Covers Models Featuring Intel Celeron, Pentium II and III Processors and the
Intel 440BX AGPset

The PCI bus provides support for the UATA controllers, USB ports, and PCI
expansion devices.

The PCI bus operates at 33 MHz.

ENHANCED IDE INTERFACE: NOTE: With only one device connected to a
controller, a 40-conductor cable 10 inches or shorter will allow UATA mode 2
operation. Two devices on the same 40-pin/10"cable will limit operation to
UATA mode 1 (25 MB/s). For a controller to provide UATA mode 2 (33 MB/s)
operation with two devices connected requires an optional 80-conductor
cable.

Pin 34 is used by BIOS for 40-/80-conductor cable detection. On the
40-conductor cable,

pin 34 is high (+5 VDC). On the 80-conductor cable, pin 34 is low
(grounded).

Reply to this Message

Ben Myers - 28 Nov 2004 04:46 GMT

Yes, the IDE drives will work just fine with an older style 40-pin cable. It's
also true form (most) other computers. With a 40-pin cable, rather than 80-pin,
the drives run slower and have fewer operational modes available. For a 450MHz
system, the difference in performance would be slight. For a P4 system, there
would be a more significant slowdown with a 40-pin cable. The Compaq manual
speaks truth... Ben Myers

>I am upgrading the COMPAQ Deskpro EN Model 6450+ (details below) for my
>nephew.
[quoted text clipped - 80 lines]
>pin 34 is high (+5 VDC). On the 80-conductor cable, pin 34 is low
>(grounded).

Reply to this Message

Lilla - 28 Nov 2004 06:32 GMT

Ben, thank you very much.

Lilla

> Yes, the IDE drives will work just fine with an older style 40-pin cable.
> It's
[quoted text clipped - 95 lines]
>>pin 34 is high (+5 VDC). On the 80-conductor cable, pin 34 is low
>>(grounded).

Reply to this Message

Lilla - 29 Nov 2004 19:51 GMT

Just a followup in case it might be useful to someone else...

I wound up trying both an 80-pin and a 40-pin cable, and decided to use the
40-pin cable, here's why. With the 80-pin cable there was an annoying
pulsating sound coming from one/both drives. When I switched to the 40-pin
cable the pulsating sound was gone.

Lilla

> Yes, the IDE drives will work just fine with an older style 40-pin cable.
> It's
[quoted text clipped - 95 lines]
>>pin 34 is high (+5 VDC). On the 80-conductor cable, pin 34 is low
>>(grounded).

Reply to this Message