Are these symptoms normal PCMark behavior, or system config issue?

[fury]

I started upgrading my 5 year old PC which had a motherboard go bad a couple years back, and I've been tweaking and getting back into the swing of things. Dusted off my old 3dmark and PCMark keys and started playing around with them. I noticed something about PCMark that seemed a little odd and indicated to me that either I did something wrong, or I am just not remembering well enough how PCMark behaved on my old system.

Here's what I got in my system currently:

New:
Antec ECO 400C
Biostar A880g+
Phenom II x6 1055T
G.Skill 2x2gb DDR3-1333
Old:
WD Raptor 740GD 74gb
BFG 7800 GT OC

Using Windows 7 Home Premium 64

I get about 7500-8200 depending on overclock. My top stable speed appears to be a base clock of 249, putting the CPU at just under 3.5, memory at effectively 1666, HT and NB at 2.49ghz, etc (all according to CPU-Z). I can't seem to push it further right now due to lackluster CPU cooling not allowing a voltage bump. On the dinosaur video card, I manage 485 core and 1200 memory before I get artifacts.

What I'm noticing is that many times the rendering window will either "lag" with a white display area, or briefly appear then disappear for some time right as soon as the test starts, and this may last 30-60 seconds before the test continues. Additionally, in the middle of some tests like where it brings up the multi tabbed browser, it will pause for a few seconds on a page every now and then.

Is it due to my aging hard drive, or am I missing something else, or is it par for the course on PCMark?

edit: Latest PCMV result: http://orb.futuremark.com/compare?pcmv=384335

[fury]

Also, I switched to a Raptor 150 gig and it's actually slower than the older Raptor 74 gig. I dunno why.

And in either case, putting my SATA controller into AHCI mode (for NCQ support) actually slows down PCMark overall by about 400-600 points.