SS2K5 64bit Dualcore CPUs Maxing Out

Hi

Settled into the new giggero now.

Since I have moved here we have upgraded our 4 SQL Servers to 2005 64 bit. All 2 proc dual core hyper threaded with 4GB RAM. Windows 2003. SQL Server compatibility level is 90. SP 1 and the CTP for SP2 are installed. We are hanging on with sp2. Maxdop is 0 (but has been tried on 2). Up to a score or so databases per machine, between 8 and 300 GB in size. Offline, reasonably heavy duty ETL batch processing.

Since upgrading we have had trouble with the CPUs intermittently maxing out at 100% usage. This is when intensive routines are run. We know that many of these routines are crappy (SELECT... INTO creating tables with 10s or 100s of millions of rows, cursors etc.) and we are rewriting the code. Estimated time of completion of code review and rewrite is end of next year so we can't wait that long. The same poor code ran (albeit slowly) in SS2k but is causing the server to lock up now it is being run on SS2k5. Symptoms include connection attempts timing out, routines running very slowly. Existing connections can continue to make requests but these are very slow. If we get on the box the CPUs are at a never wavering 100% utilisation. This continues until intervention is taken, often restarting the service. We have left a maxed out box alone over a weekend and it was still in the same state when we came in on Monday. Nothing to glean from the error logs (AFAIK).

Obviously the long term fix is to get the code sorted but this is an ongoing process (in fact it is one of the reasons I was hired). Our immediate concern is to get the servers back up to the sort of performance we were realising before we upgraded.

Does anyone have any ideas?
As ever eternal gratitude and a crate of virtual beer for any help :D