Anyway you can test the CPUs in another board? May just be bad processors. Alternately there may be some configuration "gotcha" you aren't seeing immediately - voltage, clocking, memory config, etc.

I've heard that the 486DX 50 is a problematic CPU. It uses the fastest FSB setting of any 486 CPU, and none of the chipsets that supported it worked well with it. If your board supports clock doubling, you'd be better off with a DX2 66.

Only a small percentage of all the 486 sold back then, was 50 mhz variants.
You are better of getting SX-25, DX-33 or DX2-66 versions.

I suggest you try running it as if it was a 33MHz CPU and report the result. 50MHz bus is probably stressing your motherboard, videocard, maybe even cache and RAM.

Thank you for your replies, my board doesnt support dx2 cpu's. I pulled the motherboard out earlier and found a ceramic capacitor that was broken up and starting to fall apart. It was next to the on board cache ram, so I am going to replace it and keep my fingers crossed that it may fix it. I have a feeling It may, as with the 50mhz cpu, it sometimes throws ram glitches when it locks up. Anyway, if it doesnt, I will continue. I did notice that when I pulled out the 50 and put my 33mhz cpu in, I forgot to change the jumpers, and the video still showed the funky lines kind of like static on the monitor. However when I reset the jumpers for a 33, the lines disappeared again. So its obviously a motherboard problem somewhere. Will post tomorrow what happens one way or another. By the way, the static like lines are only on 1 row across my monitor. Same row as the ram count during post. Just scattered lines that jump like crazy.

I remember getting those old boards to run at 50mhz was a trial and error deal(mostly error), same for the 40mhz DX2's.

Okay, I replaced 2 ceramic disc capacitors and it boots now using the 50mhz cpu. It still has the lines horizontally on the screen, like a video card glitch. However if i go into a game, the lines disappear. Now, to answer the previous question about will it run if the jumpers are set for a 33mhz cpu while using the 50 cpu? Yes it runs without the funky lines. It must be a motherboard problem linked to the jumper that designates 33 or 50. I have linked it directly to a chip on the board, visibly it looks fine, I may try replacing the chip and see if that clears it up unless anyone offers better ideas.
so the 50 processor does work on 33 settings. I dont know a way to check and see if it is limited to 33 or if it is actually running at 50 though.

Alright, nix the last post. I have found the problem. It is a case of a finicky vlb video card. I have a mach32 card with 2mb ram. I tried an isa video card, the lines disappeared. Put the mach32 back in, the lines came back. So, I guess I will be looking for a better vlb card. Any suggestions? I have an isa tseng et4000ax, it makes video look like it is covered in scotch tape. I have a cirrus logic vlb video card and it doesnt work at all. So, im kinda in the dark. Thank you all for putting up with me 🤣. I tried my mach32 in all 3 vlb slots and the lines were present. I just hope it isnt a vlb glitch and will cause problems with any card I put in it.

Last post, video and cpu fixed. Problem was a finicky mach32 that didn't like a 50mhz cpu. I replaced the mach32 with a diamond stealth pro. All problems are now fixed. Excellent video, no hitches or glitches. Thanks for the help.

Glad you sorted it out. VLB videocards are very sensitive to FSB speed. 50MHz is VERY high.