Shuttle (a.k.a. Spacewalker) HOT649A

"Coolest" high-end dual slot 1 motherboard with SCSI

by Derek Kwan

Shuttle's (a.k.a Spacewalker) HOT-649A is a high-end SMP (Dual) suppoeted motherboard with on board Adaptec SCSI controller and it is possible in a role of high-end workstation or even a file server.

When we open up the shipping box it contains a quick reference card with just enough information to setup the motherboard for testing. And at first we thought the manual is missing, and turns out it only come with a soft copy in PDF format on the CD.

HOT649A comes with 4 PCI 3 ISA (one share), 4 DIMM slot support up to 1GB memory, on-board dual channel UDMA/33 and SCSI controllers. This motherboard also come with a EISCA Cooler (J46) connector, we have no clue what is this for, but when we take a closer look, it is possible to connect other SMBus (a.k.a. I₂C bus) devices to the board. HOT-649A can support single or dual slot 1 processors as well as dual celerons. In single processor mode, HOT-649A comes with a CPU terminator which needs to plug into the empty slot 1. The board uses two differnet DC-DC convertor for voltage supply and it also provide a simple on board CPU Vcc_CORE voltage tweak jumper (JP49 for Slot1B & JP50 for Slot1A) allows a voltage fine tune for additional 1%, 2% or 10% over the default voltage. From the quick reference card, it only shows jumper setting for a 2x - 5x CPU clock multiplier (2x, 2.5x, 3x, 3.5x, 4x, 4.5x and 5x). But with our Celeron 366MHz Processor, it requires a 5.5x setting and at first we try to set the multiplier jumpers to AUTO and use the BIOS for setting, turns out the BIOS only show a support up to 5x also. Then we go check with shuttle's web site and finally we found the jumper setting for 5.5x ratio. And upon POST, the frequency and multiplier detects correctly. However what really puzzle us is according to the latest BIOS (649AS01F), in the change log it shows support for 550MHz Pentium III processors but a 5.5x ratio is not availabe in the SoftCPU... Meanwhile this motherboard also support a wide range of FSB and PCI frequency.

FSB Frequency (PCI Frequency)

66MHz (33MHz)	75MHz (37MHz)	83MHz (41MHz)	100MHz (33MHz)	103MHz (34MHz)	112MHz (37MHz)	115MHz (38MHz)
120MHz (40MHz)	124MHz (31MHz)	133MHz (33MHz)	133MHz (44MHz)	140MHz (35MHz)	150MHz (37.5MHz)

Note: at 133MHz FSB, user have a choice of 33 or 44MHz PCI frequency

One feature really worth to point out is the temperature managment with HOT-649A, not only it has two CPU temperature (which provide a closer reading of the CPU core than using LM75 type of sensors) and one system temperature probe, it also has the MOST FAN connectors we ever seen on a motherboard. There are total of FIVE connectors for FAN:-
- Two of them for the CPUs
- One next to the power connector, possible for power supply or harddrives cooling
- One beside AGP slot for today's hottest 3D chipsets
- One in between ISA slots, possible for chassis air intake
The only problem that we have is the board that we are testing does not register any tachometer output and shows 0 RPM in CMOS and even under Motherboard Monitor.

The SCSI connectors are placed in the lower right of the board just like the more expensive Asus's P2B-DS. HOT649-A provide three type of SCSI connectors, they are the 68 pin UltraWide SCSI (up to 40MB/s) which share the same channel with the regular 50 pin SCSI (up to 20MB/s). There is also a 68-pin connector that runs on a seperate channel to support LVD (Low Voltage Differential) Ultra2 SCSI which can run up to 80MB/s. With this design, slower SCSI device can connect to one channel, and mean while an array of fast Ultra2 SCSI LVD drives can run at their best on the other channel. Shuttle also include a very cool Ultra2 SCSI cable with LVD terminator. So far this is ideal for internal SCSi devices, but for external devices you will have to get a "external bulkhead" (IBM terms) that have a cable connect from the internal SCSI bus to a connector that is mounted at the back of the computer so that you can plug your SCSI cable to. (Asus P2B-DS does come with one external bulkhead) Or for home use, and if you don't mind, you can run your cables into the case directly.

Afterall, Shuttle's HOT-649A motherboard is a really good choice motherboard for high-end workstation and servers with its on-board Adaptec SCSI controllers. To make it perfect, we would like to see Shuttle include a hard copy of the complete manual (instead on a CDROM), as well as include a SCSI "external bulkhead". And we hope to see a BIOS update so that SoftCPU menu will support a multipiler of 5.5x and above.

Board Revsion: 649AV11

BIOS Version: 649AS01F

Number of DIMM Slot: 4

2X AGP Slot: YES

UDMA/66 interface onboard: No

SCSI on Board: Yes

Number of ISA Slot: 3

Number of PCI Slot: 4

Number of share ISA/PCI slot: 1

68.5MHz Turbo Frequency: No

Overall Score: 93

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