m4nifold supercomputer cluster: First checklist of parts

I'm lazy to compose a completely new post, so I'll just lift this from the IHIQS forums as I've written it. Now the next part is to cut the costs to a stage where I can afford the thing, and find donor nodes/parts.

"OK guys, I've worked on this for some time and I'm planning to set up a completely new rig with 4 nodes on top of the pool of unwanted PCs to boost the cluster's performance.

I wrote a spreadsheet of SSE2 benchmarks against cost, and based on MFLOPS/cost, I found the present most cost-effective processors to be the Athlon II X3-425, and very closely, the Athlon II X4-620. On comparing the power consumption, I think that the Athlon II X4-620 will make an excellent basis for this project. Going for micro-ATX for small form factor, we have

- Athlon II X4-620, 4 = S$600 (S$150)
- Biostar TA785G3 (micro-ATX compliant/AM3 socket/2.6GHz HT/DDR3 compliant), 4 = S$392 (S$98)
- Logisys micro-ATX 350W power supply, 4 = S$84 (S$21)
- Intel gigabit/PCI-e network adapter, 4 = S$168 (S$42)
- Team Group Xtreem DDR3-1333/2GB/CL9, 8 = S$560 (S$70)
- Samsung DVD-RW x22, 1 = S$34
- Western Digital Raptor 74GB/SATA2/10k RPM, 2, RAID0 = $0 (already in possession)

The only thing that bothers me is that Amdahl's 2nd law suggests that I have a memory bottle neck here, of roughly factor 2. But the same goes to the I/O bandwidth, which can't seem to be improved any further, so it should be OK.

Now... that sets my budget at S$1838 = US$1327.75. Which is still really low. I'm roughly expecting it to perform as fast as a hardcore gaming system based on two Core i7 970 processors at the moment - at a fraction of the cost, excluding the additional nodes. Making a lower-bound/upper-bound estimation, the system will come round to 65.47GFLOPS to 86.62GFLOPS.

Now, the thing is, how should I cut cost? I'm thinking there should be some 2nd hand goods out there... I'll scour eBay. If anyone has an unwanted DVD-RW to give, please let me know. ^^"