At this point, if all chips are seated properly, the most common issue is disfunctional tag ram
Check for a bios upgrade as well.

The simplest way to check for faulty chips is to swap them out. Try one W24257AK with 4x UM61512AK, and one UM61M256AK with 4x W24M512AK. If no problem occurs, go ahead with one W24257AK and all the 64K chips. This might give some clue.

Half-Saint wrote:

Jumpers are configured for 512K but the system sort of just gives me a black screen after RAM count. Anyone know what the problem is?

Did you configure the jumpers for single-banked or double-banked 512K?
If you do not have a dedicated SRAM tester, then the approach identified by lazibayer is a good starting point for singleing out the faulty SRAM. You may also be a problem with this motherboard's Northbridge. I have never had the best of luck with HOT-433 motherboards for memory and cache reliability.

I always stick with 256 Cache, even on boards that have support for 512. 256 always works with using the same 9 chips, whereas 512 can require harder to obtain chips.

I have Rev 4 of this board and I haven't had any issues running 512 cache. On the down side the Rev 4 isn't capable of 1mb l2 unlike the earlier revisions.

The only noticeable benefit of cache greater than 256K is if you want to run the system with 128 MB RAM or more, or if you insist on having your L2 in write-back mode with 64 MB of RAM.

Half-Saint: it occured to me that your issues may also be related to your CMOS cache timings. As I have noted repeatidly in other threads, a lot of hardware scenerios effect cache stability for certain CMOS timings. An example which may directly relate to your situation is something I noticed on a MB-8433UUD board, which contains the same chipset as the HOT-433. When I had 256 KB installed, I was able to run the FSB at 40 MHz with the fastest CMOS timings and the system was stable. When I increased the cache to 512 KB, I had to slow down the CMOS cache timings for the system to function stably.

I tried different timings in BIOS but it still wouldn't boot properly. In the end I gave up and just left it in the original 256KB cache configuration. Since money is again short, the board has found a new owner.