Re: OPTI-495SLC 386 WB mainboard fails to POST when powered up but POSTs after reset
Posted on 2023-03-25, 06:11
How does the "reset LED" on the POST card behave while you turn the system on and it fails to start?
Re: Help with Power switch connection ATX to AT Power Adapter
Posted on 2023-03-17, 20:49
When there´s only continuity as long as you keep the button pressed, you cannot use the switch. What you need is some kind of toggle switch.
Re: ASUS PVI-486AP4 with an 83mhz Pentium Overdrive will no longer post at full speed.
Posted on 2023-03-17, 18:09
All true, but at startup during the first fraction of a second this capacitor, if it is fully functional, has a low resistance before it´s completely loaded so it´s an additional burden for the 5V rail. If the 5V rail breaks down at startup, a new or better capacitor at this place will not help. …
Re: BIOS image collection - requests, discussion etc
Posted on 2023-03-17, 17:01
I would recommend don´t use the chipset USB here, all the EV protection components are missing. One static discharge / surge at the USB connector and the southbridge can be toast. My 3.43 is running fine but I havent found the time to experiment with different IRQ settings yet.
Re: Can´t enable Write Allocation on a Soyo SY-5TEO and a K6-2+
Posted on 2023-03-17, 16:56
Hello Jan, that would be great! The latest BIOS I found is this one: Filename 5te2.zip File size 87.82 KiB Downloads 29 downloads Thanks in advance!
Re: BIOS image collection - requests, discussion etc
Posted on 2023-03-17, 09:31
Here is the 3.43 version with all options enabled: Filename 5DXA.7z File size 110.42 KiB Downloads 43 downloads
Re: BIOS image collection - requests, discussion etc
Posted on 2023-03-17, 07:03
Will do. Maybe IRQ routing can be optimized manually this way.
Re: BIOS image collection - requests, discussion etc
Posted on 2023-03-17, 06:40
I tried the GA-586UX BIOS on several HX mainboards (same super I/O etc.) but it never worked. On the 586DX the 1st of the PCI-slots shares IRQ with the onboard SCSI chip even if onboard SCSI is disabled. The last PCI-slot is "slave only" and restricted to add on cards that comply with this ( …
Re: ASUS PVI-486AP4 with an 83mhz Pentium Overdrive will no longer post at full speed.
Posted on 2023-03-17, 05:59
Are you replacing this capacitor? Filename pvi486ap4s1.jpg File size 189.67 KiB Views 906 views I can´t believe it´s involved in maintaining 5V stable. This is the PSU´s job.
Re: Can´t enable Write Allocation on a Soyo SY-5TEO
Posted on 2023-03-16, 21:11
Thanks Horun, you just inspired me to try a regular K6-2. It´s also detected as "80486DX-S @ 66 MHz", but write allocation c a n be turned on with "setk6d" now. Same goes for a K6-III. Still not sure what the reason might be.
Can´t enable Write Allocation on a Soyo SY-5TEO and a K6-2+
Posted on 2023-03-16, 17:35
I have been tinkering a bit with this mainboard recently. I added the headers for a 2.9V VRM, upgraded L2 cache with an additional COAST stick for 512K in total and flashed the latest BIOS. I can now use dual voltage CPUs like the MMX233. Next I installed a socket 5 / socket 7 interposer with …
Re: ASUS PVI-486AP4 with an 83mhz Pentium Overdrive will no longer post at full speed.
Posted on 2023-03-16, 17:20
Is your PSU 100% o.k. beyond all doubt?
Re: 486 board with UMC 8881E/8886B: The winner is: EDO without L2 (terms and conditions apply)
Posted on 2023-03-15, 07:46
Voltage drop at the 1N5400 might be even higher @ 1.5A: Filename 54xx_drop.JPG File size 32.87 KiB Views 1742 views
Re: Simm for ga-586dx board. Which and where…
Posted on 2023-03-14, 07:57
It´s dual voltage and it auto-detects the presence of dual voltage CPUs and sets Vcore accordingly. All is perfect here. Just fix the x3.5 multiplyer issue with a pull-up resistor at the BF0 pins, insert 2 x MMX233 and RAM as you like and it´s maxed out.
Re: Simm for ga-586dx board. Which and where…
Posted on 2023-03-14, 07:37
Don´t get me wrong, it´s not about the colour of the heatsinks but about the fact that they are present! Why not post a picture of your board??
Re: Simm for ga-586dx board. Which and where…
Posted on 2023-03-14, 07:25
All GA-586DX with the two golden heatsinks at the CPU sockets DO suppurt dual voltage. I haven´s seen one without so far. There´s only one (non-5V) core voltage available - 2.8 / 2.9V for Pentium MMX (or single AMD CPUs). There´s also a seperate 3.3V regulator for I/O etc. Due to severe(!) BIOS …
Re: Upgraded cache but...
Posted on 2023-03-13, 14:09
I guess one (or more) of your 15nS cache chips was (were) faulty or out of spec. You definitely don´t need 12nS for 40 MHz.
Re: Recapping motherboards - no non-low-ESR caps existing (anymore?)
Posted on 2023-03-11, 20:26
On these old mainboards, without step-down regulators, you can use "general purpose" electrolytics, or Low-ESR types. It doesn´t matter, because they are just local buffers compensating transients and doing some filtering etc. What was the test frequency when you measured 0.5 Ohms ESR? I doubt they …
Re: ABIT AB-AH4 / AB-AH4T Write Back L1 Cache
Posted on 2023-03-11, 18:17
According to the datasheet a seperate "dirty SRAM" chip is supported. I wonder if this could be added some way? 85C496_cc.JPG In the meantime I upgraded to 512K L2 and 32Kx8 TAG. There was a 16Kx8 TAG chip present for the 256K version that should have been 32Kx8 according to the manual. 64MB RAM are …
Re: ABIT AB-AH4 / AB-AH4T Write Back L1 Cache
Posted on 2023-03-11, 11:08
Setting "Cache TAG Bits" from 8 (default) to 7 makes the difference in memory throughput performance in my case. When I set it to 7 the speedsys benchmarks are very similar to thoseCoffee One has: 486SPM_7bit.JPG 486SPM_7bit_sp.JPG I´m not sure what the reason is here, do you need 8-bit for larger …
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