Soyo SY-5EHM Motherboard Evaluation

General Impressions

We tested this motherboard with Intel, AMD, Cyrix and IDT chips. All of these were supported without problems, but the big news is that every Intel and AMD K6 processor we tested would run flawlessly at 100MHz. Unfortnately, neither the Cyrix nor the IDT chips would work at this speed. While the chipset is labeled ETEQ, it is actually a VIA MVP3 chipset that Soyo decided to rename, for some odd reason that eludes us.

This is a very nice product, though it does have some limitations in the number of PCI slots and SIMM/DIMM slots. We would have preferred a layout similar to the R581A, but that is not what we got. Overall, the performance is good and the 100MHz bus speed is awesome. Our K6-300 gained over a 5% performance boost by running it at 3.0 x 100MHz rather than 4.5 x 66 MHz. The 1MB L2 cache, asynch PCI/AGP speeds, and a host of BIOS/Jumper options makes this a very configurable board, though it could be a bit confusing for the novice.


Obviously, the most important feature is the fully functioning 100MHz bus setting. We tested several Intel processors, including a Pentium Classic 150MHz, and all of them worked at 100MHz without so much as a hiccup. The same can be said for all of the AMD K6 processors we tried. The only disappointing news was that neither our Cyrix processors (up to the PR233) nor the IDT (225MHz) would work at the 100MHz bus setting. It is possible that some fooling around with jumpers and BIOS settings might have gotten the PR233 to work (it stalled right after POST in our tests), but rather than make a claim for something that must be fiddled and fussed with, we feel that this should not be considered possible. It appears that the problem is with the processors, not the board.

Soyo decided to implement the bus frequency and clock multiplier settings via DIP switches, rather than jumpers. With available speeds of 60, 66, 68.5, 75, 83, 90, 100MHz and 112MHz, plus multipliers from 1.5x to 5.0x (in .5 increments), users should have plenty of options to play with. The voltages documented on the Quick Reference sheet are 2.2v, 2.8v, 2.9v, 3.3v and 3.52v. This should be enough to get any current processor up and running. The rest of the voltages from 2.0v to 3.5v are detailed in the full manual found on the CD. There is also a jumper to set the SDRAM frequency to either the CPU (system bus) speed or AGP bus speed, and one to set the Host Bus frequency to either 66MHz or 100MHz. These settings provide for maximum flexibility in setting the CPU to run at 100MHz, even if you don’t have fast SDRAM available. The PCI and AGP speeds run in ‘pseudo-synchronous’ mode with bus speeds above 66MHz.

One limitation is that there are only 2 SIMM slots and 2 DIMM slots, though the documentation claims the board will accept up to 768MB of memory, though with 1MB of cache, the cacheable memory is 256MB. The DIMM slots will accept a 128MB SDRAM or EDO module, while the SIMM slots will accept up to a 64MB EDO module. The BIOS provides for plenty of memory tweaking options for those who wish to squeeze the last bit of performance out of the board, as well.

Probably the biggest limitation of the board is the inclusion of only 3 PCI and 3 ISA slots, one of which is shared. This means you had better use an AGP card in the single AGP slot, or you will run out of PCI slots very quickly! Soyo did include both an AT and ATX power connector, which allows the soft power-on/auto power-off feature to be used. Of course, the usual array of IDE, Floppy, serial, parallel, USB and IrDA connectors are included.

Cool and/or Unique Features

Obviously, the coolest feature of this motherboard is the inclusion of 100MHz and 112MHz bus speed settings. Unfortunately, the 112MHz bus setting results in an AGP bus speed of 74.6MHz which could cause some compatibility problems with AGP video cards


The SY-5EH is a rather small AT form factor board, 8 5/8 inches by 9 1/8 inches, which limits the amount of real estate available. By including only 3 ISA and 3 PCI slots (1 shared) Soyo has prevented overcrowding, but at the same time has almost forced the use of an AGP video card. 5 card slots can be used up pretty easily. The 2 DIMM/2 SIMM configuration is also a problem.

Other than the above limitations, Soyo has done a decent job of using the limited space on this board, except that two of the 3 ISA slots will be unable to use full length cards. One potential problem is that the DIP switches will be difficult to get to when installed in a case, as they are right in behind the drive bays. A final consideration, though minor, is that the BIOS chip is directly in front of the card slots so replacing it will require removal of most add-on cards, even if you have a slide out motherboard rack.

Compatibility & Stability

All processors we tested worked well on this motherboard at their rated speed. The IDT C6-225 chip was recognized without problem, as was the K6-300. We experienced no crashes while running Winstone97 tests at both 66MHz and 100MHz bus speeds for any processor that finished booting (an issue at 100MHz).

We tested several brands of SDRAM, including Micron PC100 SDRAM, without any problems at all. We also tested EDO and FPM modules, which worked as well. Either PC100 SDRAM or 50ns EDO is recommended for stability at 100MHz bus speeds. You will see slightly faster performance with SDRAM due to the timings.

The stability of this motherboard was very good. We never experienced a timeout, or any other error in dozens of Winstone tests with various processors at various bus speeds. While we did not try to push things too far, it appears that this board can handle quite a lot of ‘tweaking’ without any problems, which is especially good for those who may want to try various settings as a learning experience.


Unfortunately, Soyo has taken the direction of only including a Quick Reference sheet in hardcopy. If you want to read the details of setup and all of the options, you will need to get that from the CD that is included. Obviously, this cuts down on expenses and the problem of reprinting for revision changes, but there is something comforting about having a hard copy manual that is easy to find if you decide to swap processors several months down the line.

On the positive side, the CD documentation is in HTML format and includes several FAQs, all motherboard manuals (PDF format), product information on all motherboards, drivers and utilities. The FAQs include an explanation of memory, bus mastering, ultra DMA, AGP and other topics of interest.


The one thing that makes this board desireable is the solid 100MHz bus speed option. Had they followed the lead of M Tech by using the layout of the R581A board, this would have been a sure fire winner in the Super 7 arena. However, until there are more motherboards in this class to choose from, the SY-5EH board is a nice product – unless you need more than 5 expansion slots.

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