Have an ancient 486 motherboard & am experiencing major problems during upgrade to a Cyrix 486dx2-66 from Intel 486SX-25 Thought it would be simple enough, to just reset the jumper setting accordingly for the new CPU and speed. The original jumper setting for Intel 486SX, 25 MHz being JP1 Enabled Normal CMOS & Password security (Blank Default) JP2/3 Intel 486 (Link Default) JP4 Enabled for CPU’s not SL – enhanced (Default) JP5 Non-interlaced monitor JP6/7 <33 MHz Local Bus speed JP8 Enabled Onboard local-bus video (Default) JP9 25 MHz External CPU speed (Others options are 33 MHz, 40 MHz) JP10 Other CPU (Not Intel 486DX2 with write-back cache support, AMD 486+) JP11 Enabled Onboard local-bus IDE (Default) JP12 Blank, not Intel DX4-33,Cyrix or Intel DX4-50 JP13 Without CPU internal coprocessor JP14 Linked as not Pentium Overdrive burst disabled JP15 Blank as not Cyrix M6, M7 JP16 Write through as not Pentium Overdrive (Default) JP17 Link as not Pentium Overdrive CPU (Default) Oakleigh Systems LCHPO.4B motherboard For the Cyrix 486dx2-66 ONLY altered the following jumper settings JP9 33 MHz External CPU speed - Previously link at 25 MHz JP2/3 Link for Cyrix (write-back) – Previously blank for Intel 486 JP12 Link Cyrix Previously blank After which the monitor screen was blank & indicating it was either suspending operations or entering a power save mode as shown by a flashing LED. Additional info that may be applicable is Memory 64MB recently added TVGA9400CXI Integrated Windows Accelerator Any thoughts on the matter guys

take out the ram you added.

JP 8 and JP13 look like possibilities. does the board have a video connector? JP8 says 'enable on-board local bus video' so you might have a conflict there. Also JP13 is 'without CPU internal processor' and I think the Cyrix DX does have the coprocessor.

Thanks for the idea. Tried all you suggested but to no but I'm still looking at a blank screen & a flashing Green light. * Disabled the Onboard local-bus video (JP8) * Added link for 486dx CPU & above (JP13). In answer to your questions 1) The board has a video feature connection plus a standard VGA connector 2) The Cyrix 486DX2 has a coprocessor comparable to the Intel version (I guess). Just one thought do you know if the Cyrix 486DX2 is a Cyrix M6 or M7 type because JP15 needs to be set if it is?